The K-bar is crucial to prevent you from becoming a log when you're expecting company but can't see it coming. You can't fire a grenade right next to your in close quarter combat; not only would that be suicidal but it's tough to aim it.
I see where you are going with this and I'm not saying mauler needs to lose the knife. Just questioning what a defensive explosives class is doing stabbing people in melee combat. It sounds kinda silly thematically.