>>528117384
NTA, skullcrusher blessing defines the weapon. Mark III has good horde clear with heavy-light-repeat, and strong overheads with light into heavy spam. The move set is a little awkward to get used to, similar to how relic blade works, but it's pretty rewarding once you get the hang of it.
For the second blessing I've had the most success with hammerblow for extra impact, letting me throw shit around. High voltage should also be good, but I haven't tested it that much.
For perks, I've had the most success with flak + maniac, both mostly for ragers. I don't think it's good enough against carapace to warrant using it against crushers. The special is great for opening up bulwarks, but the unyielding damage is also a little disappointing.

Overall, the weapon is actually a little disappointing. It's very mid and has poor cleave, but it's about to receive major buffs. I'm not sure how good it'll be on other classes, but the actual reason it'll be used on arbites is skullcrusher working on monstrosities with picrel, swapping over to bolter or fire shotgun, and obliterating them. Or just whacking the weak spot for team support. You're nearly doubling damage.
The class also gets the crusher, which also has skullcrusher.