It could be like 5 motes of light to add a light level to your armor until you get to 32 light, then you have to etheric light it to 42. It could work since motes are kind of a dead end currency now. It's always miserable to get a really cool piece of gear but having to shard it because it's blue. If ttk weapons get light levels like what was shown at E3 then strike rares could get this as well. Maybe you could even do something to get it to legendary status and add the additional perks to it. Then there's the amazing idea of a multi stage branching quest that upgrades your Khvostov into a custom exotic weapon with a somewhat unique history.