Let's say, for instance, we add three things:
- Some considerable WAR undermechanics such that its defensive capacities can ramp from its offense, such as by overhealing from damage dealt briefly increasing (the addition fades rapidly) current and maximum HP or Defense. This is to compensate for the flavorful downsides of Berserk such that WAR has some slightly unique optimizations and feels more distinct.
- Some reason for other players to be near the WAR. This wouldn't likely be a change to Berserk itself, but perhaps instead a passive War Cry mechanic that can affect Infuriate, Thrill of Battle, etc.
- Penalties (not net penalties, just... in itself) for using Berserk. Ideally, by having Berserk, say, gradually build up towards Havoc (your attacks have a chance to partly cleave nearby allies) or even outright Bloodlust (like Confusion, but with bonus attacks against friends and foes alike; no real penalty if you're the last alive, haha). Perhaps gain Wrath (Beast Gauge) from damage struck, but also increase the chance of being critically hit by enemy attacks while Berserk is active (again, the WAR-specific flavorful forms of mitigation as tied to offense would be enough to compensate for this).
Voila: You'd actually feel like you're going Berserk. You could maybe have Equilibrium help with this in some way, or revert Shake it Off while giving it a second charge and maybe some synergy in form of a CD or passive granting damage-delay (a portion of damage taken is instead divided up to tick per second over 4 seconds).