Grenadier

Grenadier is a passive skill, unlocked at level 45.

In-game
Grenades concept covers not only the respective skill, but also all other skill runes that may launch grenades. It even affects its own post-death grenade.
 * Cluster Arrow (All Skill Runes except Shooting Stars and Maelstrom)
 * Grenade (All Skill Runes)
 * Rain of Vengeance (Anathema)
 * Rapid Fire (Bombardment)
 * (Demolition)
 * (Personal Mortar)

Obviously, the second bonus is useless for Hardcore characters, but some exotic builds do utilize it as a way to soften up particularly hard foes.