I'm tempted to boost my Relic of Xuen but I'm not sure if that would be a wise choice over one of my 489 Daggers? Especially If in the next couple of weeks I just replace them with heroic versions and or the Spiritsever from ToEs.
Well, it only takes 1.5 weeks to get enough valor to fully upgrade something, so don't think of it as a lifelong commitment. You are going to get the best bang for your buck by upgrading your MH weapon. I'd save it for a heroic piece, but I don't see any H kills on your armory yet? How close are you to killing Lei Shi? Do you save your extra rolls for her? It took me 7 weeks + extra rolls of H SG kills before I got the dagger, so don't think of it was something that is' guaranteed to happen soon
Are you capped on valor? If you think you're going to get a shot at H SG next week, for example, maybe you just halfway upgrade your trinket or you weapon, just so you don't cap out on valor, and save it for possible drops next week. If nothing drops next week, upgrade the rest of the way? Even if the dagger dropped from Lei Shi or H SG, you would still use the upgraded one as your OH, which isnt a huge DPS upgrade, but it wouldn't be totally wasted.
My approach: weapons are top priority, after that the armor/accessories I expect to be using longer (example, any normal mode gear over any lfr gear, and late-boss normal mode over early boss normal mode, etc).