That's exactly the kind of stuff that creates disgruntled customers and incites people to participate in fight club antics to acquire them for free in the first place. Falling into the arbitrary limitations trap too many times, then having someone explain that it still works in the content that was out when you bought it. How many people paid to grind phlogs faster only to learn after the fact that their weapon now works in 2 levels of content? How many people bought timers in advance only to learn they wont work in new content?
How long before metagaming becomes learning an increasingly long list of stuff and which eras of the game each item works in. Will these limitations be specifically listed in the item descriptions or will people continue to pay for them only to find out afterward that they don't work in the content they try to use them in afterward.