An auxiliary safety mechanism for a grenade to prevent detonation from shockwaves, heat, fragments, etc., the grenade including a fuse housing containing a delay detonator and explosive train. In at least one embodiment, the fuse housing includes a reversible slider element interposed between the delay detonator and the rest of the explosive train to form a barrier therebetween when the grenade is in an unarmed condition, and when the slider element is withdrawn the barrier between the delay detonator and explosive train is removed leaving the grenade in an armed condition. In another embodiment, a further safety mechanism involves connecting the two sections of the housing with a weak connection that ruptures prior to the explosive contained therein reaching the critical explosive temperature/pressure.