Then why not an extra joy? Getting out of bad luck situations at the cost of health is their precise function.
You can't give him a smart bomb because the one thing keeping you from using them, score, doesn't exist outside of stunting your upgrade progression.
And a parry or dodge roll would be disastrous because it would remove 90% of the need to position and manipulate enemies, or manage health. Japes is already barely affected by an amulet supposed to nullify him; we don't need him to turn into yet another character who can just block everything either.