Mummelmann on 12 May 2016
Ser Jorah deserves to be fairly high up on the list, when he enters the hostile city with Grey Worm and Daario, he easily holds his own and shows some immense skill with a blade. Bronn's greatest strength is his somewhat dishonest fighting tactics, he doesn't shy away from any means to win, as shown in second fight in the show (trial by combat against a knight and still one of his best quotes ever).
Jaqen H'ghar is another mystery entry; this character is obviously really, really deadly, more so than anyone else mentioned in this thread, but his skill in open combat is hard to gauge, he relies on subterfuge and stealth. But there is no denying that he is the most efficient killer of them all, at the very least.
