How to steal items. You should walk next to an enemy carrying something that you want to get and try to lift it.
To increase Mage's Spirit With Sacrifice, go to the healer and press X at your mage's name. Then you can pick an item you want to sacrifice.
To view alternate ending, complete the game 2 times and get at least 80% of the side quests done. Hold L1+R1 before the second end scene.