Aether -> Unless you're willing to wait for Wrath/Resolve, this and Provoke is all Ike needs. MUST HAVE.
Astra -> Meh. Swordmasters are better off with Adept or Wrath. Pass.
Boon -> Very helpful if you forgot a Restore staff in Chapter 29 and Endgame. Keep, since it's already there.
Blessing -> Reyson's already got it. It's pretty nice, though. Keep, since it's already there.
Cancel -> I don't use the hawks much, and Tibarn is around for too brief a time to really make use of this. Pass.
Colossus -> Boyd already deals lots of damage, he doesn't need this. He's better off with Adept or Wrath. Pass.
Deadeye -> Snipers should be scoring criticals on enemies, not putting them to sleep! Pass.
Flare -> I don't use mages to attack a whole lot, and Occult can be put to better use. I'd rather have Soren keep Adept. Pass.
Lethality -> If only Volke scored criticals more. Pass.
Luna -> Decent skill for Generals and Halberdiers, and cool to watch. Defense-piercing is a nice touch as well. First time I used this I stuck it on Brom, with good results. Keep.
Roar -> Why stun an enemy when you can kill it? Pass.
Sol -> Great skill for Paladins, who are already pretty godly in this game. I always stick two of my Occults on Oscar and Kieran. For Mist, I'll pass. She's better off healing anyway. MUST HAVE for Oscar and Kieran. Pass for Mist.
Stun -> Not exactly great. You might as well just kill the enemy rather than stun it. Pass.
Vortex -> I never use Naesala in the last battle, but I suppose it can be useful. Keep, since it's already there.