Lol, perfect representation of the AC VI tutorial experience.
It's the infamous first boss from AC VI, got a lot of fame thanks to it being a gatekeeper to the rest of the game thanks to how hard it is to beat. It's the way the game has to check if you really know how to play.
Judging by your playtime I thought you had stop at that point. But don't worry, you'll understand if you ever decide to go back to it.