Great set! :) Makes me want to make a little NES game with them.
A few ideas:
- A ranged weapon for both characters. Maybe a bow & arrow for Knight and throw-able spears for the Orc?
- A wooden treasure chest (closed and open)
- A "special" treasure chest (closed and open) -- This could contain rare items
- A staircase to go up/down like in a roguelike
- Gold coins that the character can pick up
- Heart, half heart and empty heart - Can be used for health indicator and as an item that can be picked up