The only problem with 'any' card system that has 1 or 2 cards that give a direct damage increase, is that those are the 'only' cards any of the 'meta players' will want. They will just go back to 'fishing for balance' again.

Your Bole, Spire, Ewer and Balance cards are good alternatives, but Anything resembeling 'balance' (such as your Spear/Arrow) will just bring us full circle to the 'fishing for balance' that's caused them to gut our card system in the first place