Enchantments last X% longer...

Does this modifier only apply to those enchantments you cast or does it include those cast on you?

I believe it refers to the enchantments on YOU whether you casted it on yourself or someone casted it on you.

This is a good question. I really don't know the answer.

I always assumed it meant enchantments you cast on yourself or others.

Its enchantments that you cast, either on yourself or an ally. Enchantments cast on you by someone else are not effected. Also, the duration of the enchantment is calculated on cast time, so you can equip your +x% enchant duration item, cast an enchantment, and then switch to another item while keeping the added duration on the enchantment.

Ones you cast on anyone, as far as I know.

Hmm... I'd always presumed that these were effected as well, and is why I carry an axe with a +19% on enchantments. If that isn't the case, then it's a wasted upgrade since I hardly ever actually cast them myself.

Can anyone else confirm this?