Based on what I've played so far, I don't understand the point of durability on anything other than chest armor and weapons.
I think they were going for something like Fire Emblem, where weapon durability was a key thing to be aware of during lengthier battles. In FE, you always needed a backup weapon because there was no repairing, and weapons disappeared permanently once they hit 0; this could leave even your best warriors defenseless and useless for the duration of the battle
unless there was a replacement weapon. This mechanic sometimes meant frantic item-transfers occurred in the later stages of a battle.
Unfortunately, Divinity's implementation of durability seems off-kilter. Weapon durability has only mattered when bashing objects, and at times it feels like that's the only reason it's there - to discourage very resilient doors from being destroyed. (I still managed in spite of this.) Armour durability has likewise been
completely irrelevant. For instance, I've repaired the 10 durability Zandalor's Trunks item
once so far - and that's been equipped on a front-line warrior for the majority of my playtime.
It really seems like Larian might have intended for something else earlier in development, perhaps an acid element that damaged equipment. But at the very least, they put it in so modders would have a crack at using it.
Bonus comment: ZOMGWTF you can resize the posting box on NEOGAF?
#gamechanger