Any chance we could have maybe 2-3 exclusive cosmetic items for the weave leaderboards, and every month the monthly leaderboard resets and award the top groups in each weave with 1 of the cosmetics for each member of said group each randomly from the pool for the weaves? It need not be unique cosmetics for each weave, maybe just a pool that functions for the whole thing.
The reason I suggest this is I think it would be somewhat cool and exciting to compete for some exclusive cosmetics each month. If it works out, it might remain interesting if there where more added to this pool over time, and a mechanic in place to prevent repeats.
One more thought on this, what if for each member of the leading group in each weave who somehow manages to collect the entire pool that exists at the time of awarding the cosmetic, provides randomly to a member of the next group down the leaderboard for that month of that weave, one of the cosmetics.