The Short-Fuse Frag Grenade is a thrown explosive weapon variant used by the Soldier class in Tribes: Ascend. It can be unlocked for 120 Gold or 14000 XP. This weapon is often banned in competitive play.
"This modified XL grenade has had its fuse shortened, giving enemies less time to respond." In-Game Description
The Short-Fuse Frag Grenade is thrown just like any other grenade in Tribes: Ascend. What makes this weapon so powerful is that it's radius is quite large, thus almost guaranteeing a hit, and it's fuse is so short (about 2 seconds) that enemy players rarely even have time to see it thrown, much less react and evade it. This also means of course that the Soldier who threw the grenade is in danger of being hit by it..