A simple pistol that shoot bullets.
However, when the bullets hit a surface, they explode. If it's a direct hit, it'll do 75 damage to the player. If caught in the blast radius, it'll only do 30.
The blast radius is fairly small, but can launch a player a fair distance if the bullet explodes at just the right time.
It can also destroy small bricks.
Sounds balanced to me.
(I am aware a rocket pistol exists, but it's a little overpowered)