I don't want to sound like an arrogant prick, but how does one struggle with any mission from AC series? In terms of difficulty, AC games have always been unbalanced in my opinion, you can finish the story in 2 days without any kind of rush. Same goes for AC3 - the game wasn't challenging at all, I don't remember a single mission, which I had to repeat at least 2 times.
Vinny, if you are on PS3, you should get God of War 1&2 and go for Platinum. After you achieved that, no AC3 mission will ever be hard to you.