[ Suggested by: @toxic dawn ]
It would make sense to remove soulbound from quest card boxes.
The reason for this is that the great majority of these boxes are traded anyway. You just give your weapon to the person who has the box and have him/her pierce it for you.
So there's no benefit at all of having these boxes being bound, since they end up with the players with money anyway. Actually it only has disadvantages: If you want to sell the cards, but have few contacts in the game, you won't get rid of them, because you won't be trusted. On the buyer's side, there's the risk that you'll be scammed and your weapon, in which you've already invested a lot, will be gone. It's only a matter of time before someone quits because he/she was scammed.
So since there is no advantage and only disadvantages, I think it's reasonable. The fragments to get boxes can remain soulbound so you still need your 50 runs per character.
-> Addition from @last rampart : Please make them stackable