He enchants the slotted items from the NPCs Ophaine and Sharick.
There's a 1% chance your item can break when you try to enchant it.
Possible Enchants:
STR+1 (4700), INT+1 (4710), DEX+1 (4720), AGI+1 (4730), VIT+1 (4740), LUK+1 (4750), MDEF+2 (4786), DEF+3 (4791).