I feel like people might be interpreting the last page wrongly, I feel like the one that did the 'sealing' was Gaolang. On page 15, it looks like Fang's going for a kick but is forced to block instead. And from Rama's dialogue with Metsudo, it implies that Fang is being forced onto the back foot rather than willingly using boxing. But that's just my ten cents on the matter. All will be revealed soon enough.