|I think it's probably nothing serious. Otherwise his shirt would've been bloodied or something.
Spoiler (mouse over to view)
On the other hand, you never know. Maybe he was so interested in the Bokor, because he was desperate for info about how to cure his wound? He's clearly a super intelligent guy, so he probably realizes how dangerous it would be to try and capture the Bokor, therefore he must have a reason as to why he wanted to study it.
This is such a great manga. Very interesting characters and plot driven. Can't wait to read more.