Remnant of a Warrior
Yes, you’re meant to fight him twice: once to basically jog his memory, and then the second time to prove your worth. And yes, the second fight is meant to be a bit more difficult. This pattern is repeated in the following steps of the chain, too. Honestly, I didn’t find it to be a difficult task for this fight; I did get downed once in a later fight with a different character, but it was all still manageable. All of the big attacks are telegraphed very clearly.
FWIW, that bar is definitely breakable, it just takes a lot of CC. My necromancer experience (where everything is a soft CC eating it away) and my non-necro experience involved very different amounts of bar breakage…