Halvar, God of Battle looks fine to me. The front side's ability to move equipment around is somewhat interesting, but I would value
Ardenn, Intrepid Archaeologist's ability to equip for free over the ability to equip during opponents' combats. Double strike is pretty useful, at least. On the flip side, Sword of the Realms looks interesting. Not the most efficient in terms of stats, but protecting creatures from removal (or enabling recursion shenanigans) is pretty nice. I can't think of many other mono-white commanders that can do something similar. Overall, I don't think either side is amazing, but it's possible I'm undervaluing the flexibility.
From a card design perspective, I appreciate that these flip-legends are playable as a 4-of in other formats. Being a more 'mortal' god is also nice, since it's consistently been the most obnoxious part of other gods. I'm also a sucker for flip cards in general. Plus, having an equipment as a commander seems sweet.
Kaya the Inexorable looks fine. Following the
Ob Nixilis Reignited template - (+1) generates card advantage via token production / creature recursion. (-3) exiling any nonland permanent is really nice. (-7) is a little niche for an ultimate, but the base case is to just recur Kaya and exile a thing every few turns, which isn't bad. When you start building around it with
Karn's Temporal Sundering or just cheating stuff out, it gets significantly more potent. I can't think of any Orzhov walkers with a comparable removal ability, so she seems worth testing out.