He was a warlord, yes, but not an Iron Lord. If you want more info on him, Shaxx had fought and won against Felwinter multiple times (read the short story if you want more context here https://www.ishtar-collective.net/records/remembrance , hopefully I got that link right). He did work with the Iron Lords temporarily I believe, but refused to take the Iron Creed, along with the title. This post was also written before we knew Shaxx was previously (or I suppose, still is) a Warlord, so you’ll have to excuse me for some lapses in information.

I know almost all of Shaax's history