@HeySlickThatsMe The chainsaw may work with the mini gun animations. Not sure how that would look on a melee weapon, or if you can make a melee weapon be "rapid fire" so damage is continuously applied.
Also yeah there is a flame thrower mod out there, however it doesn't go very far because of the limitations on the used effect. However, in the Arena War DLC, they added a flame thrower as a vehicle weapon, and that will likely work nicely.
Flashbang would definitely be scripted. Apply a timecycmod and then its intensity decreases (taking 5 seconds). During that time, the drunk walking animations can be used.
Side note: Does GTA V have that ear ring sound effect that GTA IV had when an explosion goes off near you? You'd hear a ringing sound and the audio would be super muffled, and that would fade.