Maybe he's a scam? A sort where he enables internal corruption in kingdoms to win by willingly losing in wars? Because we should consider the fact he's a mercenary. He said it himself, it's not about politics, it's about profit, so whether they win or lose they get the money. So then, how much easier it is to lose than to win a war? But obviously he needs to make it look real, so then that's where his strength comes in. It's that he's so powerful, he doesn't need to risk anything even when losing, he just offers the opponents their victory.