On siege, there could be a point shop (for items bought for ever) They could sell items like- extra protection and feather falling when you vote, you get an iron sword instead of a iron axe for the orc soldier. iron helmets for gondor on the maps were you don't get them. The non-donors could only purchase the boost, but never upgrade it. (They could buyiron helmets, but never upgrade it.)
Lords could upgrade it once, Legends twice, veterans three times, sages 4 times, and king 5 times. For the donors, the upgrades would beworth something very small, like 500 points per upgrade or something like that. This would mean no classes, just the donors get upgraded items, that the non-donors get too.
A list of upgrades here
Iron Sword for orc soilder 5k points (only 500 points for donors)
Iron Helmet for gondor/rohan 5k points (upgradable for donors, (to get added Prot. and golden helm), 500 points
Prot. 2 Feather falling 3 when you vote- 7.5k (only 500 points for donors)
Strength I for 2 secs after a kill-10.k (Upgradable for donors, plus 1 sec each upgrade, 1000 points per upgrade)
Diamond Sword for gondor soilder 15.k points( 5% chance) (Upgradable for donors, 1500 per upgrade))