To be honest, Mahal was truly perplexed. Why would this man named Long Yi give so many battle armors to him, to help him out in such a manner? What's in it for him?
In fact, Long Yi's thoughts were simple, no matter what world it's in, where there is sunlight, there will inevitably be shadows. Right now, what the two great empires represent is sunlight, but shadows will always hide where the sunlight can't reach. And to find the prey lurking in the shadows, one must enlist the help of those who already dwell within them.
And the pirates, they were Long Yi's breakthrough. Maybe Long Yi still didn't know what he might need the pirates for, but what he hoped was that when the time came for them to do something for him, his word would carry significant weight.