Prequel stuff. The Wadjet regalia is not armor, there's some protective magic woven into it, and Rath can summon it via the amulet, but it gives no power and was made independent of the amulet. It's mostly ceremonial.
The design however is supposed to be somewhat proto-armor, the cobra hood being just a linen hood with a headpiece that he can put back or remove entirely. There is a 'tail', but it is a length of cloth with a weight at the end, nothing more. Useful for grappling or smacking someone in the face at distance.
Pharaoh Thutmose has this made for Rath after a battle I am still working out the details for in which he ends up saving both Thutmose's and Amenhotep's butts (he also gets his sword in this battle). Rath is actually happy about this because he's still wearing novice robes and nobody takes him seriously. He wears it until he is released from his oath.
In the second part of the prequel with all four guardians of Rapses, when Rath is added to the team, he of course initially goes back to using the regalia. Magically, it fits perfectly, and yet he doesn't feel like it fits anymore, because he's not who he was. It's Armon who finally suggests he stop using it, as there's too much memory bound to it of which Rath can't let go.
After the defeat of Hathor in the team's first big adventure together, Rath stops wearing the regalia, sticking to his chief magician attire. However, he does tend to call on it when shit hits the fan.
Now he's got kickass power armor with his own magical girl transformation sequence he don't need that sub-par shit anymore.
Please ignore his fucking shoujo hair.