Weaknesses.
Mentally, Sasuke normally comes off as composed, in which most of the time he is. However, he can be easy to snap if you know his weak points. Naruto is his first weak point for sake of downright frustration. Naruto knows Sasuke almost better than he knows himself. Sasuke is very conflicted with his emotions when it comes to the blond.
The Uchiha's mind is constantly working, conflicting, and overall being stressing. A lot of Sasuke's confidence is a bluff. He is a great actor in this area but is actually extremely self conscious. He is a perfectionist and is never satisfied with himself. He is very hard on himself to the point of self destruction. While Sasuke comes off as stable and level headed, inside he can be a very large mess in which he has no idea how to deal with. He is constantly looking to prove himself and his worth.
While Sasuke excels intellectually and physically in anything he takes on; he is weak in the area of emotion. He is vulnerable, uncertain, and often downright stupid in this area. Relationships whether friends, or if on the small chance or by character development, romantic - will never be a joy ride. He has been beaten and battered to a pulp emotionally by Orochimaru, by Itachi, by even himself. Even before the slaughter, when he was young, his Father was often cold to him. Furthermore, Sasuke has not developed his emotions due to his obsession with revenge. In many senses, Sasuke is still emotionally five years old.
This brings him to his last massive flaw. His brother. His brother is like an addiction. Thinking of Sasuke as an addict would get the point across very well. He simply cannot live without him. Even now that he is not psychically weak against him; Itachi was (and still pathetically is) Sasuke's life. He is the gravitation pull of Sasuke's entire being. It is his hatred that binds them. His biggest psychological, and emotional flaws lie here in their twisted relationship. He losses 85% of any sensibility around his brother. This has changed drastically due to the "truth". He is still very unstable in the topic of his brother, however the reasons have changed.
He's also a bit of a trauma case. As in, he has severe PTSD. He has built himself a bit of a guilt complex because his world is dying more or less due to his failure. Though tables have turned, many things still haunt him.
Noteable Possession
Aside from his abilities and his eyes, Sasuke has a chokuto named Kusanagi and wields it very well. He is also more than proficient with shuriken. Also able to summon the real Kusanagi from the pit of his stomach. His body could be considered a weapon too.