When Desmund is tripping out as Altair and you're climbing the tower, there's this bit where you can't proceed until you work out how to do this jump that looks like it can be done another way.
 
I spent 25 minutes bashing my head against this tiny freakin' jump, can't be more than 2 feet, but Altair just REFUSES to make the jump. After giving up and looking it up online, it turns out that you have to run up the wall slightly then jump off it at the height of your wall-run at an angle to make it. 
 
This is easily 100x more challenging than any fight in this game. Boy oh boy.
 

Dude, spoilers.

I completely agree. Worst section of that game.

" Dude, spoilers. "

" I completely agree. Worst section of that game. "

Are you talking about where it's kind of that little balcony with the wooden board overhead?

If you're right below a post, you can hold right trigger (or Rwhatev on Playstation) and just hit A.  He'll jump straight up and grab it.  But yeah, the ninja-ing was not helpful right there.  Something about AC1 geometry with AC2's climbing mechanics, or something.  It was a weird, messed up design flub. 

" Are you talking about where it's kind of that little balcony with the wooden board overhead? "

" I got pass it pretty quickly. But, who was the girl? "

" @TheGTAvaccine said:

" Are you talking about where it's kind of that little balcony with the wooden board overhead? "

If it's this part, then... no, it's not the most challenging part in the game. I mean, it took me a while to figure out how to do it, but it wasn't that hard. You just sit on the balcony's railing and jump straight up rather than towards the wall. "

I totally agree then, that part was a pain in the ass. However, the hardest part in the game for me (and the only thing I had to look up online) was the glyph that is near the boat that you take later on in the game.