better damage as I have seen
Well from my time playing the heart shows how close you and the companion are at say 10 they usually let you edit their appearance and stats for the ones in the tavern once high enough they will not leave after a dungeon and will stay with you along with allowing editing of stats. For companions you meet outside the tavern once they like you enough by fighting with them you can take their weapons away so you can use them to farm EXP