In Tales of Vesperia there are objectives the player can do during most boss battles in order to complete an optional secret mission. There are 23 secret missions from boss battles along with several others and they all must be done on Normal mode or harder. Completing all the secret missions unlock the True Knight costume for Yuri. It is recommended that these are attempted on your second playthrough since you should have certain bonuses from the Grade shop carried over that makes these missions easier. The first 23 secret missions detailed are the ones from the boss battles. After those, there are the rest.
- Secret Mission 1
Description: Defeated Zagi while protecting Estellise from Zagi's attacks
Guide: The first battle with Zagi happens when you arrive in Flynn's room. It is easy for Estelle to stay back and not take much damage because Yuri should be doing all the damage here. Be sure to free run and guard often so Zagi won't be able to get any combos on you.
- Secret Mission 2
Description: Downed Goliath by attacking its Achilles' heel while it charged X Buster.
Guide: When Goliath is charging his X Buster attack simply go into free run, go behind him and start attacking the glowing blue part on his leg.
Video Tutorial: http://www.youtube.com/watch?v=FQ8Uz9KrEio&feature=related
- Secret Mission 3
Description: Learning from Karol's experience, you used the billybally plants to stun Gattuso.
Guide: Gattuso is a tough boss so it does help if you can stun him. Don't ignore the cubs and be sure to go into free run for some of his attacks can cause a lot of damage. Lure him to one of the orange plants which are on the outside perimeter of the fighting area and target the plant when Gattuso is next to it. Use azure edge and it should be stunned.
Video Tutorial: http://www.youtube.com/watch?v=_X0eupJ1UFo&feature=related
- Secret Mission 4
Description: Lured Zagi to the side of the ship and knocked him overboard to cool him off!
Guide: In order to do this you must lure Zagi to the side of the boat and have him attack you. The hardest part is actually luring him because he will just attack your other party members instead of you. Make sure that your party members have their strategy to Avoid Risk for HP, not use TP, and to keep distance. Azure edge Zagi until he comes near you. Guard and keep doing so until he does his cyclone arte. Activate overlimit when he is above your head and he will go over.
- Secret Mission 5
Description-Downed the Dreaded Giant when it reared back and left itself wide open
Guide-Wait for it to stand on its hind legs, at that moment run and slash at them. You will want a multi-hit attack since you need to bring down the shield first before the attack will knock him over.
- Secret Mission 6
Description- Raven used Serpent to set a trap for the Gigalarva and prevented it from healing itself.
Guide-Use ince Gigalarva has less than 24000 HP. The way to do it is to take control of Raven for the battle and once Gigalarva is down below 24000 hp stand in front of it and cast Serpent. Whenever Serpent runs out or Gigalarva moves away simply cast or re-position yourself and recast it.
- Secret Mission 7
Description- You took out the bridge supports, thus keeping Barbos from calling more of his thugs.
Guide-Easy, target the bridge supports and destroy them before taking out Barbos.
Video Tutorial: http://www.youtube.com/watch?v=rDv2UzNkNhw&feature=related
- Secret Mission 8
Descripton-Let Zagi absorb too much energy, destroying his bodhi blastia
Guide-Stand back and don't attack. let him absorb aer until his blastia explodes.
- Secret Mission 9
Description-You defeated the Leader Bat and prevented Pteropus from recombining.
Guide-After Pteropus splits into his bats, just have everyone go after the leader bat and well... kill it. Judith is helpful in this battle because of her aerial attacks.
Video Tutorial: http://www.youtube.com/watch?v=RaF6IFrluIQ&feature=related
- Secret Mission 10
Description-VS. Outbreaker. You destroyed the core and prevented magic from inverting day and night.
Guide- Wait until Outbreaker spits out it's core. You'll only have a small window of opportunity here so it's best to have Judith once again because of her aerial attacks. Rita with a well timed Tractor Beam spell should work well also.
- Secret Mission 11
Description- VS. Belius. You lit up all candlesticks and eliminated the illusions.
Guide-For this achievement, Yuri and Rita are very helpful. Get Belius down to half of her health or so and she'll split in two. Be sure to use a Magic Lens on her clone for the Monster Book. Afterwards, target the candlesticks and have Rita use a fire spell or Yuri use Destruction Field to light them
Video Tutorial: http://www.youtube.com/watch?v=HbDIsTMwCYw
- Secret Mission 12
Description-VS. Nan and Tison. Timed your strikes between their attacks and knocked them down.
Guide- This one can be a bit difficult. Nan and Tison both have attacks where their weapons get stuck in the ground. You have to time your attacks to just hit them while they're stuck. You don't need to do them both at the same time, individually is fine. A good Azure Storm should put them in their place.
- Secret Mission 13
Description- VS. Schwann. Downed him by attacking when he was clutching his heart after his mystic arte.
Guide-Just the Description says. Wait for Schwann to use his mystic arte, Blast Heart, then run up and hit him while he's still clutching his heart. A good Azure Storm or Ghost Wolf Strike should do the job
- Secret Mission 14
Description- Fourth battle VS. Zagi. Used Karol's Nice Recovery Smash arte to force him to recover from poison.
Guide-A very easy achievement. Make sure you have Karol in your party for this one. Once Zagi posions himself partway through the battle, just run up to him as Karol and use Nice Recovery Smash.
- Secret Mission 15
Description-VS. Baitojoh. Hit it 3 times during it's Ice Edge attack and fished it out of the water.
Guide-Wait for Baitojoh to dive underneath the battlefield so that only his fin sticks out. Give him a good Azure Storm or multi-hit move and it should work.
- Secret Mission 16
Description-VS. Estellise. Used the item, Mother's Memento.
Guide-Make sure to get the item Mother's Memento from a scene in Mantaic. To get it, you have to sleep in the inn after you visit Yormgen I believe. Once the battle starts with her, just use the item. I can't remember if you're supposed to use it in the 1st or 2nd battle with her so use it in both to make sure. It doesn't go away don't worry.
- Secret Mission 17
Description-VS. Yeager. Made his heart explode using Raven's Rain arte.
Guide-The infamous Secret Mission 17. Hardest one to get. I only just got it on my fourth play through. But anyway, I'll list several tactics. After Yeager reveals his heart, one tactic is to just have Raven sit back and spam Rain in overlimit. Another is to have Yuri go into overlimit, spam Destruction Field on Yeager 4-5 times then pause. If Yeager crouches over from the damage then switch control to Raven, go into overlimit if you can, then use Rain. The last way I know of that I used was to put the game into Hard difficulty so that the battle lasted longer so I had more chances of doing it. Surprisingly, I was successful.
- Secret Mission 18
Description- VS. Alexei. Downed him by attacking when he was tired after his mystic arte.
Guide-Exactly the same as Schwann. Wait for him to use his mystic arte then hit him with somebody a few times. Once again, a well timed Azure Storm does the trick.
- Secret Mission 19
Description- VS. Gusios. Attacked his tail, then downed him with a close attack while his feet were raised.
Guide- Basically the same thing as Dreaded Giant since it's the same creature. Wait for him to raise before he goes down. Hit him and you'll get it.
- Secret Mission 20
Description- VS. Khroma. Downed her by timing your strikes between certain of her attacks.
Guide- Khroma has an attack when she makes rocks fall from the sky. The goal here is to hit her while she's doing that but before the rocks come down. As soon as you see her start to go up, a good Ghost Wolf attack should do it.
- Secret Mission 21
Description- VS. Flynn. He used every arte he could, including a mystic arte.
Guide- A list of Flynn's artes are Demon Fang, Tiger Blade, Sonic Thrust, Sword Rain:Alpha, Beast, Demonic Circle, Demonic Chaos, Dragon Swarm, Guardian Field, First Aid, Holy Lance, and his mystic arte Radiant Dragon Fang. He'll only use his mystic arte if you use yours on him first. He DOES NOT have to be in overlimit. He'll activate it as soon as you activate yours. Just try to keep track of everything he uses and keep Yuri healthy. You should be fine.
- Secret Mission 22
Description- Fifth battle VS. Zagi. Downed him by attacking after he becomes exhausted from Blastia Bane.
Guide- Kind of the same as Alexei. Zagi has a move called Blastia Bane that he uses. He gets more tired after eery use though. After he uses it, just give him a nice Azure Storm. After you beat him this time, he finally dies. We think.
- Secret Mission 23
Description-Defeated Duke using a mystic arte.
Guide- This needs to be done in his second form! Once he gets between 10,000 and 15,000 health, just stick someone's mystic arte on him. As long as you kill him with hit, you'll get the achievement.
 Other Secret Achievements
Description- Whoa! Easy! Could you be any faster?! Relax. Take your time. There's much more to discover...
Guide- Beat the entire storyline in 15 hours. I've yet to attempt this but it's supposed to be a little difficult. You're going to want to do it on your 2nd play through or higher. You're going to want 2x-10x the experience along with bringing over weapons and items.
Description-Hey! You answered every quiz question right! You are a true Tales fan. Thank you.
Guide- choose these answers while Rita is taken her Miska test thing on Nam Cobanda. The answers are September 30, 1998, Raine, Bubbles, Presea and the option about turning to stone.
- Ahhh, Memories
Description- You have cleared the Labyrinth of Memories. Did you enjoy the surprise?
Guide- The Labyrinth of Memories is also known as the EX Dungeon. To actually beat the dungeon, you'll need 15 fake gald, that you find inside the the place, along with defeating the Traitor to Heaven, otherwise known as Kratos Aurion!
- Bunny Guild Member
Description- Somehow, somewhere, you became an official member of the Bunny Guild. Who needs Brave Vesperia?
Guide- After getting a pair of bunny ears for Yuri, Judith, Estelle, and Rita, equip them all for a total of 5 hours and you'll get the achievement. You'll get the bunny ears from the old man in the Union Headquarters in Dahngrest.
- Low Level Challenger
Description- You defeated Barbos at Lv. 15 or under! Amazing! You sure know how to take this guy down.
Guide- Just like it says. 2nd playthrough or higher and make sure that at the end of the battle you'r only maybe level 14 just to be safe. Avoid any little battles along the way and bring powerful weapons from the last playthrough.