It is actually really easy to do this stuff yourself, dude.

Just open your Medieval directory (C:\Program Files\SEGA\Medieval II Total War\data or wherever else you installed it) and open up the file export_descr_unit.txt (make sure you've unpacked it first - see thread https://forums.totalwar.org/vb/showthread.php?t=76289). The file has instructions on editing already in it, so you shouldn't have much trouble figuring it out. Just be sure to make yourself a backup in case you screw up.