Was a while ago on wowhead so you’ll have to give me a bit of time to find it.
It’s related somehow (think this sword wielded by one of the morgraines in the Shadowlands or smth) but it isn’t the ashbringer.
"It’s still a bit unclear how he can still wield a version of Ashbringer alongside players with artifact weapons, but maybe that will be a fun lore tidbit saved for the Maldaxxus covenant campaign.
We have seen many legendary powers inspired by past set bonuses and Legion legendaries, so perhaps this weapon has the essence of Ashbringer, but is not actually Ashbringer"
So it has a slim chance to be the ashbringer but it seems unlikely.