I kind of agree that it’s a bit boring but not especially overpowered.
I think a change that would solve both is giving it a more interesting and more powerful charge up. Since the charge up attack is so fast now, there’s basically no difference between an uncharged zap and a fully charged zap, so there’s no tactical decision to make between them.
Like with the plasma gun or helbore, the thing that makes charge up weapons interesting to use is that fully charged serves a different purpose to uncharged. In both of those cases, fully charged is much stronger but also much slower, so one would typically use uncharged shots against weak enemies and charged shots against big targets. You don’t bother using charged up shots on weak enemies because it’s a waste of time.
I think the surge staff might be more interesting if it was an inversion of this: What if charging the surge staff didn’t increase its damage, if it always did very high damage to a single target, but charging it up made it chain to more targets, with all secondary targets taking only, let’s say, about half the damage, and it had a really long potential charge time. Something like, able to charge for up to five whole seconds, below 0.75 seconds of charging makes the bolt strike only a single target, and then one chain is added every .25 seconds above that. A fully charged strike would do lots of damage to the main target, and then substantial damage to like twenty other targets, enough to kill them if they’re weak enemies like horde guys or shooters.
I believe this would make the surge staff effective against single targets by spamming low charge strikes, and useful against groups with high charged strikes, which would be interesting to use because the psyker would always be weighing how long they’re willing to keep charging before releasing a strike as enemies approach them, not to determine how much damage to do to a single target, but to determine how many other targets they can get away with hitting.
It wouldn’t be that good at disrupting groups since striking lots of targets requires charging for a long time, but that’s okay, because that’s what Smite is for. Smite disrupts, Surge kills. It also wouldn’t make the surge staff outpace the other three staves in terms of horde killing, since they would still charge up faster and so be more reliable against hordes, thus keeping the surge staff still in its role of being the best at killing big priority targets like ogryn or specials.
oh also the surge staff should have a cooler sound effect, now that it’s a high damage weapon they should put some serious thunderclap in there or something