Vaas kills anyone who looks at him the wrong way and has a frighteningly obstreperous personality who is feared even by his own men, some of whom are as chaotic and mentally unstable as Vaas.
Vaas is a highly skilled planner. He orchestrates his pirate groups activities. He uses a spotter to lure people to his island to ransom them only sell them off later anyways. Vaas is skilled in methods of torture such as sand burial, pulling teeth, electrocution, and exposure to phobias.