It depends on the rest of your build, @SOLDIER_1stClass ... there's no "one enchant to rule them all".
Some players like Weapon Damage enchant on one dagger and Crusher enchant on the other. Enchants should definitely be different on main hand and off-hand.
The trait edge is often Sharpened on both daggers ... but if you've already built for enough physical penetration that opens up other possibilities.