Two ways maybe more as I can see it being added without it being outdated by next gear ilvl.
1. The weapon with skill trait on it can be researched by you or freind crafter and then able to learn it, but it destroys said item and then can attach/overwrite on a more current weapon/gear.
2. Upgradable weapon or gear where you go threw sets of trails similar maybe to relic perhaps were the stats increase as the ilvl increases keeping them relevant.
Just couple of idea of maybe imo.