So vaders now lost again to obi wan. He loses a lot doesnt he. Maybe he just aint all the good.
Vader can/does defeat 99 out of 100 opponents he faces, Obi-Wan is his blind spot. It’s been well established his obsession/anger to prove himself to Obi-Wan. It’s beyond personal.
I don’t think this fight detracts from his overall aura or anything. Look at the way he ragdolls almost everyone else, from Reva to the hallway scene in Rogue One etc. With Obi-Wan, there’s too much history there for him to deal with it seems.