It was a speed dampener, not a metahuman dampener. No speedsters allowed. Which brings the question if Argus had that tech why couldn't the guys at Star Labs get that device from Argus and use it against Savitar?

I just rewatched the show and the exact words by Cisco was "that is a metahuman power dampener. It's all over the building so you can't use your powers inside."

Ok, my bad. But if such a device exists then why not use it to stop savitar? Why not use it to stop all the bad meta humans? You can't expect to see logic on this show, the writers are complete idiots! Like last season with Zoom, Cisco's exact words were " The man can literally open a portal to other dimensions". Talking about Zoom, then their brilliant idea on how to stop Zoom was to send him to another dimension. Umm Hello??

Yeah, it's tech Cisco developed in season 1. They used it when they were transporting rogues, and is no doubt the basis for the necklace they made for Caitlyn. It really should have been the first thing to try against Savitar. Hell, I thought for sure Future Cisco's gizmo that interfered with Barry returning to the present was going to playing into defeating Savitar; and that was before they revealed that Savitar was an iteration of Barry...

the whole show is broken now and it only holding by a thread. I think they are either trying to fix it with just wally for a while or they are just gonna dig deeper into their own grave with their idiot writers going crazy trying to rewrite the laws or reality.

I think "Legends" of Tomorrow is pretty much clear evidence of the latter....