The Ebony warrior says he want's to go to Sovngarde even though he is a Redguard, but if you visit Sovngarde after doing the quest where you fight him, he isn't there. Does that mean he hasn't gotten into Sovngarde? That's pretty unfair considering some random Stormcloak soldier runs up to you.Could the Ebony warrior have been devoured by Alduin? Is Sovngarde exclusively for Nords?

Tsun's battleaxe has a base damage of 27.Does that make it the strongest battleaxe? The Daedric and Dragonbone battleaxes and Wuuthrad come the closest with the base damage of 25,26 and 25 respectively.

Note: I haven't considered tempering or any sort of perks.

People tend to give too much in-universe thought to thins that are merely an oversight. Regardless if he "canonically" ended up in Sovngarde or not, he's not there most probably simply because devs didn't think about it.

There are plenty of people killed in the game who don't end up in Sovngarde, I wouldn't read too much into that. Its more a gameplay mechanic than a definition of lore.