Keteᛕ

Only reason I can think of is that it kinda forces Szeth to give up fighting. He’s no longer radiant at that point, so he can’t get it back(idk if he even could if he was radiant, Nightblood does some crazy things) and with one arm, he’d lose pretty much every fight. This kinda just signifies that Szeth is done, he gets a mostly peaceful life(as much as one can under the night of sorrows)

okay, so they both had the same arm at the same time, leading to a temporary collapse in the space time continuum, which, via Hoid, was able to be fixed.

Therefore, Hoid must have gone to braize, and messed up Chana’s soul to make her start a desolation. Then, after hearing about the man in white, he gave Nale Nightblood, as to make him be around something conveniently able to eat his arm. And then when Szeth didn’t get eaten by himself, Hoid sent Kaladin to make sure it happened 

Yes