Question on "enchants last x% longer" Weapon Mod

How does it works exactly? The bonus duration triggers only if you hold the weapon WHILE casting(so you can swap out and still have a longer effect)?

If someone else casts an enchant on you (While you are holding the modded weapon) does the mod still work? Or he has to wield it?

You can use +20% enchant weapon, then switch to another one without the enchant's duration going back to normal.

If you are wearing a +20% enchants weapon, and someone else casts an enchant on you, it will not get +20% duration bonus, the caster must have the enchant bonus.

As long as you have it equipped when you cast the enchantment, it will have the 20% bonus.