Thunker: Thanks
But how can i find thoses hidden treasure ? I use the spell and a little potion of perception but can't find : some compagnions have a better chance to see hidden things ? I'm with The first compagnion and Diabolus
I don't think they turn blue/visible until you've activated the relevant quests. They're still present on the map, but if you click on them, you get a "the chest is locked" message. At this moment in your playthrough, both caches are completely irrelevant.
Companions have no skills other than their ability to deal and absorb damage.