So far, the most damaging (per hit) weapon I've tried is the Legia Bow. With Power V, it normally does 27-36 damage per hit on unarmored targets. The Crystal Bow might do more damage over time, since it fires much faster.
As for melee weapons, the most damaging weapon I've found is the Ender Giant Sword, which regularly does 16 damage with Sharpness V, and can do 20 or more with critical hits.
It's unfortunate that TC weapons aren't that great compared to what's available. The Legia Bow, in my opinion, is not nearly costly enough for being the most powerful ranged weapon in the game (it only takes iron, wood and string to construct)