Well to be fair, I did mention a movement penalty when charging the weapon and also a rather long charge-up time. So your basically making yourself vulnerable to archers and spidertons, since you can't block with the weapon in general. Also being unlocked in mid to late game may mean it will be rather easy for you to get swarmed and overwhelmed. Sure, massive damage, but your putting yourself at huge risk in the process and basically need to take a strategic approach.
Viewing post in New Weapon Idea: Energy Staff
yeah, the basic idea of this weapon is interesting, and all the tradeoffs like negative effects while using it etc would have to be worked out in implementation after some playtesting.
Massive AOE attack, comes with increased exposure/slowdown/energy cost.
The hammer is already a small step in this general direction. Will think about if we want another one that has more range!
Well dang, I honestly didn't expect to get this much attention for this idea. I'd just thought it will be an interesting thing to share. But anyways this, or another similar weapon, if ever implemented would be an interesting change of pace for the player. I don't expect this to be an easy weapon to use, in fact I expect it to be one of the most; if not the most difficult to use. Which is what I kind of want out of this idea. But undeniably, this weapon will likely be far more complex than the rest and would take time to properly balance, like you mentioned.