Unfortunately, adding Hit to weapons by spending PDs is only really done as a very rare GM-hosted event. Once in 2017, once in 2015, and I don't know before that. It's not a gimme, not assured, and it's pretty much the only way we'll get it. Given World of Illusion's existence and nature, it's pretty likely the "best" players would resume the four-man grind for PDs for days like what's happened in the past.
Something permanent for the server would probably have to reflect what happens with adding hit to Monster Part weapons. Increasing quantities of the trade-in item per attempt, item lost on success AND failure, more chance to fail as you go, caps at 50%. I'd figure "risk 10 Photon Drops for a 100% chance to boost your weapon from 0% to 10% hit" leading up to "Risk 50 Photon Drops for a 20% chance to boost your weapon from 40% to 50% hit" is a low enough ceiling and hard enough grind to be a possible balance.