We've datamined a new Axe model in Season of Discovery Phase 4 — and it looks like the Axe of Cenarius, wielded by Broxigar the Red!
Broxigar's Axe of Cenarius is a weapon deeply steeped in lore. According to Warcraft Wiki, the Axe of Cenarius was specifically made for Broxigar by Malfurion Stormrage.
Broxigar himself is legendary for using this axe to physically wound Sargeras — one of only two mortals ever to have done so.
An image of Broxigar wielding the Axe of Cenarius, courtesy of Warcraft Wiki.
While we don't know how to get this Axe, it certainly looks like it's related to the Emerald Dream, or possibly the Emerald Nightmare. We do know in lore that the Axe of Cenarius was recovered after Broxigar's death, and in Retail is currently in possession of Broxigar's niece, Thura.