If the collars (cuffs) are plastic they will probably come free using a bit of heat to soften them, e.g. a towel soaked in boiling water, or a heat gun. I had to heat them to put them onto my oars.
Mine have just been varnished and I haven’t had any problem with that. I don’t tend to row for hours and hours though.
I would have thought that epoxy might not have the flex for use on oars, but that’s just speculation on my part.
A glass-cloth bandage epoxied over the ends of the blades will help stop them splitting, and will protect them when you inevitably start using the oars to punt or fend off.