The Arcstriders have gotten themselves an upgrade they weren't meant to. In the aftermath of the TWAB update for Destiny 2, a bug has entered the game. In the update, it enabled the Arcstrider's Combination Blow melee ability to be stacked three times. The problem comes in when a super is done with the triple-stack in place, as the buff rolls into the super.
What's more, quick successive attacks with Arc Staff increase its damage output and duration when wearing the Raiden Flux chest armor. While this is a problem, it has not garnered an immediate fix. Bungie did make a note stating the following:
"We are looking intro Arcstrider supers and their ability to achieve higher-than-intended damage against bosses when mixing certain perks. Until fixed, you may notice bosses in Gambit or other activities being pummeled into the ground by Hunters and their Arc Staffs."
There will be updates on the start of the investigation; with that said though, it is likely that Arcstriders will continue being the top dog until sometime next week.
On another note, other issues with the update such as a bug that enabled pinnacle weapons to be picked up at no cost have been fixed. It's been announced that the Wavesplitter can no longer be acquired or equipped by players on non-PS4 platforms, and Sentry Armor will now grant appropriate perks in Gambit Prime.