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).