When Jin looked at his beloved old weapons, he noticed that there was something a little different from them. Their handles and hilts had been redesigned to the point where they incorporated Bamboo elements in it, making their name even more prominent for Bam and Boo.
But that was not the only thing that had been changed for these two shapeshifting weapons. A core had been added to the weapons themselves and only upon analysis that Jin find out that these cores were not just random magical cores.
It was actually a living breathing chi based core. There was chi being generated within it and if Jin could utilise it properly, it could also act as another chi generating item for him. That was what he had discovered when he first saw Bam but the moment he saw the Boo also had a core, Jin assumed otherwise until he looked at it carefully to notice that it was not a chi core but a mana core.