They look similar to a normal frag grenade, but bear a painted-on white cross. When detonated, Holy Frag Grenades explode in a manner similar to a mini nuke. This being said, the grenades deal a whopping 800 damage, but require no skill and little Strength to use effectively.
The grenades also have a positively enormous blast radius, comprising just over 70 feet. Characters with Splash Damage or Loose Cannon will have a difficult time escaping the blast. The inner 23 feet of the blast zone will be irradiated at a level of 5 rads per second, but the radiation should dissipate after about 10 seconds.
Three Holy Frag Grenades are located in the basement of the church in the eastern part of Camp Searchlight, guarded by two golden geckos. It will only be available to players that have the Wild Wasteland trait. Players without the trait will find two mini nukes in the location instead.
If the player originally did not chose the Wild Wasteland trait, but later switched to it using the Auto-Doc in Old World Blues before taking the mini nukes, then the Holy Frag Grenades can still be obtained.
Behind the scenes
The cult hit Monty Python and the Holy Grail started the Holy Hand Grenade joke, which was previously featured in Fallout 2 with the Holy Hand Grenade being obtainable from a Special encounter. Specifically, this weapon is a reference to the Holy Hand Grenade of Antioch. Operating instructions along with the numbers 5 (crossed out) and 3 is another reference to the aforementioned movie.
PCPlayStation 3Xbox 360 If dropped, the Holy Frag Grenade may be stuck where it is dropped. While they can be picked back up, the player cannot freely position them for display.
PCPlayStation 3Xbox 360 When thrown, the projectile's model is that of the normal frag grenade. As such, the model doesn't appear to have the white cross on it.