And smoke bombs, and computers, and hand to hand (or mostly kicks), grapples and throws, he's good in a LOT of things. He's one of the few villains who can regularly take down the main villain. Though most other heroes can usually beat him.
If anything, he's sort of an anti-Batman. Has high intelligence, amazing with lots of gadgets and weaponry, very stealthy. The prime differences from Batman is, he's willing to kill, he's a thief, assassin, hired gun, etc., and, he's not willing to fight females. Also, what would make him difficult for Batman to fight, when was the last time you seen Batman fight a kid?
He's not a Batman fanfic character, but I built a lot of his skills as an anti-Batman.
He's not an evil character. More, neutral, just villains tend to hire him a lot.