The shield breaks faster when attacked by monsters. I asume everyone knows about it. But only few people (i think) knows that it breaks faster when atacked by party members.You want to try it? Just equip your sera, use 3rd skill and count seconds. Then ask someone with highest asi and make him attack you (ofc count the seconds again. Have fun testing!
So I was talking with my friend and he thinks it is not worth to spend points on "Cover" so there is lesser chance that people will attack the shield. But there are 2 problems: Cover also increases duration of shield and you cant choose ultimate form of skill until its maxed.But if you are wearing chaos or somehow earn CTR Max other way and you wanted to upgrade it to valkirian aura you dont have to spend skillpoints on Cover.
when they use the shield to cross over a long stretch of spikes, cross with them. It ends up breaking and they usually take damage but not you.