Trade Delve Weapons back to NPC for 1/2 or 1/3rd plasm cost?

Is this a possibility? Once we upgrade from our Delve weapons to Relic / Mythic / Empyrean, can we add this as a feature?

For example, Oatixur costs 200k plasm. Can we trade it back to NPC (one-time!) for some percentage of Plasm? (10, 20, 30%?)

Thank you.