CON + 1.
Atk + 3 and P.Atk + 1 per 20 base CON of the user.
If the enchanted equipment is grade D, additional P.Atk + 1 per 20 base CON.
If the enchanted equipment is grade C, additional P.Atk + 1 per 20 base CON.
If the enchanted equipment is grade B, additional P.Atk + 1 per 20 base CON.
If the enchanted equipment is grade A, additional P.Atk + 1 per 20 base CON.