According to the subreddit, the wiki, and one of ENB's videos, Artorias' attacks are harder to dodge in generally do to a difference in his weapon and animation speeds vs his damage actually being done or registered. Apparently they differ from the rest of the game probably due to being a dlc.
Me? Suck? Not quite, it's just a pain in the ass to fight a boss that doesn't have reasonable patterns, the same dodge mechanics as the rest of the game, with no shield one handing a claymore, and only silver knight armor and wanderer's leggings.