The Repellent Stick is a unique quest-related melee weapon found in Fallout 3 designed to ward off Mole Rats, though it unintentionally has a far more fatal effect on them. It is a simple stick soaked with an unusual, green substance at the tip.
Craterside Supply, Megaton
Upon completing the mole rat portion of the Wasteland Survival Guide quest, if the optional objective of using the repellent on seven more mole rats is fulfilled, the player is able to keep the repellent stick for future use. If the optional objective is not fulfilled, or if the quest is completed with a speech-based lie, Moira takes back the stick but will sell it to you from that point on, meaning you can still have it permanently if you accidentally or intentionally did the bare minimum. If in the future you don't have the repellent stick and you want it, it can be found by lockpicking the desk upstairs (hard). Be careful while doing this, since if you take it this way it may not be taken out of your inventory. It will be considered a quest item.
In the Citadel, a terminal exists that contains notes on development of biological weapons; specifically a genetically engineered invasive animal species that could severely disrupt Chinese food logistics. It also came with a "kill switch", allowing American forces to easily dispose of the vermin. If the Mole Rats are descendants from the prototype transgenics that escaped from the labs in the wake of the Great War, then Moira may have stumbled upon the kill switch in the form of her Mole Rat Repellent.
The repellent effect will not register if you incidentally occur instant kills of the molerat, such as through the sneak attacks afforded by the Chinese Stealth Armor or Stealthboy. You will not get credit toward the completion of the quest unless the repellent has the chance to work on each mole rat before they expire. So, when using this weapon to complete the Wasteland Survival Guide quest, do not use sneak attacks to kill the mole rats.
The Repellent Stick is a simple wooden stick with Mole Rat repellent on it. The stick is exceptionally effective against Mole Rats, as one hit causes an allergic reaction on Mole Rats, causing their bodies to smoke and their heads to explode in a few seconds, while a second hit will cause the explosion to happen instantly. Do not be fooled by what Moira says when you first get this stick, as it's an experiment gone wrong. Moira will exclaim "Poor little mole ratties!" when she realizes it does more than chasing the Mole Rats away.
Also - When hitting a mole rat with this with the Animal Friend perk, all mole rats in the vicinity will become hostile. Be careful what you do with it. With the perk "Superior Defender" this weapons damage modifier is maxed to a damage of 10.
The Repellent Stick also seems to be effective on Radroaches.
- Xbox 360 and PC: If you convince Moira Brown to give up on the book, she might not take the repellent stick back. You can not drop it because it says it's a quest item. But, If you answer her question about how the stick worked using charisma you will be able to keep the stick as a normal object.
- PS3 & Xbox 360: If you pick the lock on her desk, there is a repellent stick. If you take it when you have already finished the quest, you cannot drop it because it's a quest item.
- PS3 & Xbox 360: It is possible to buy the repellent stick back from Moira directly after giving it back following completion of the quest, without completing the optional objective. The stick appears in her inventory. However, once you buy it, it is treated as a quest item.
- Because it's a quest item, if you enter the Operation: Anchorage simulation, The Pitt, or are taken aboard Mothership Zeta before you complete the Repellent Stick quest, you will keep the stick in your inventory even after the rest of your equipment is taken away.