I love how everyone is saying Aram is mentally unstable, therefore it hinders his swordsmanship. There a numerous passages in the book that speak on Lans mental instability. A man who wishes for nothing more than to die in a futile war he cant win isnt exactly the most together person in my opinion, but Lan uses that. He is fearless, he has nothing to lose.

 

Aram is very much the same. He may be a bit tapped in the head, but he lost his parents and most of his family to trollocs, watched most of it happen, then had the remainder of his family call him Lost for desiring to stop it happening again. He doesnt believe in the way of the leaf any more, he belives in that sword, the sword is his purpose in life. Much like Lans was before he was bonded.

 

Lan's pretty cool about it though. He doesn't drool at the mouth and he doesn't show a total lack of concern for himself and others as Aram showed in the end.

 

For however much Lan was supposed to get his irrational revenge on the Blight, he never did just throw himself into a pit of trollocs needlessly. Even before he was bonded to Moiraine, something led him to survive up until that point, and kept him from committing suicide in a one man charge on Shayol Ghul. He honed himself into a weapon with a specific idea in his head and that focus was sane. He knew he could not just waste himself, so he trained his mind and body to become a man who could walk into the Blight and perhaps even could make it  to Shayol Ghul. That's focus.

 

Aram, he had nothing but the sword. He had no purpose. His people shunned him and in the end Perrin could barely stand the sight of him. He became a sociopath who fought for no other reason than to satisfy his own twisted vision of himself. 

Aram maybe 75 but gets his butt whip if he faced Lan,or Rand.