From another thread:
I was thinking about this further. Maybe my suggested new runes idea could also be used to improve existing raid loot or maybe turn the runes in with old raid loot for better versions?
Lynnabel has shown SSG has the tech to do that with the Schism Shard turn-ins for better versions of Wave, Whelm, and Blackrazor. Why not do it for older raid loot as well?