Washington coach Todd Reirden said Reaves was targeting Wilson the entire game.
"You could hear it on every face-off, you could hear the things that were being said, and it's a blindside hit where an unsuspecting player hits his head on the ice," he said. "That's disappointing. You can put two and two together, but he targeted him the entire game."
The Golden Knights killed the Reaves penalty and scored two goals in 16 seconds early in the third period.
Bellemare tied it 2-2 at 2:33, and Eakin got his 200th NHL point when he scored for the 3-2 lead.
Vegas was 4-for-4 on the penalty kill.
"[Golden Knights coach Gerard Gallant] kind of challenged our group in the third period, challenged our group to be harder, smarter, better in all aspects of the game," Schmidt said. "It was a feeling in this room that, if we kill this off, we have a chance to grab the momentum back."
Vrana scored his second of the night at 11:40 to tie it 3-3.