About skills: Damage skills/spells increase damage and reduce de cost. Non-damage skills/spells double reduce de cost.
The magical itens are rly bugged, I recommend to load an early save before getting them. It will be fixed in the next update, but the fix don't work on itens already in your inventory, so don't take the magical items yet. Unless if you don't care of having to repair them.
well, i was suspecting this, but its too late for me to turn back to previous save i overwrote the same slot crap!! thank you for confirmation, i may think i start again and skip that dungeon maybe i mean i wont open any chest there ... i may keep the current save if you need the name of a certain item, cause some even are accesories that i have without "unbreakable" and they are like the earrings from prolog with special effects also so i think those should be too and are bugged..