Forsaken knight gear is very good and only a few stats less than the donation counterparts (which is also available through voting), so you can't really use that as an excuse for dying. If you have the knight and legendary gear, the right cards and strategy, you can absolutely be competitive in PvP and kill donors - many people have said the same in other topics. I'd definitely ask around for suggestions on strategy and take the time to learn how PvP and such works here, it will be well worth it. :) And try not to jump to conclusions when you haven't been here long enough or have enough experience under your belt to know how PvP really works.
As for your suggestion: I like the idea a lot and think the concept is interesting, however, I'm worried that adding these new legacy cards would result in veterans camping the MvPs and making it even harder for newbies to get MvP drops/cards. This is already a bit of a problem here now, and this would make it a lot worse. :/
Based on that, I think perhaps the more viable option may be having an NPC that exchanges x amount of a card for an upgraded legacy version of the card. Though that would probably have similar ramifications, too... does anyone have any suggestions on how we could address this? I do want to make MvPing more of a thing here, but at the same time, I don't want to hurt newbies either.