I use Hot Glue to assemble all of my paddles
I never have failures or leaks... but it would be very simple to heat the handle, loosen, add more hot glue and reset it.
Anytime I want to change a blade or handle, I simply heat the area with a heat gun.
Be careful not to use too much heat, as carbon becomes brittle when over heated.
It doesn't take a lot of heat to melt hot glue