You may also want to hold on to your Glory points, then use them on a week that features a weapon or new troop that uses brown/purple. The 400 glory packages also toss in two arcane stones. Perhaps 400 glory for two Arcane may not be efficient but it would provide another way of gathering Arcanes without grinding or breaking out the wallet…just have to be patient for that week to appear.
EDIT: Sorry thought he meant purple/brown! At least my point still stands, I actually like how the new weekly weapon/new troop packages for 3-400 glory were implemented. I like getting some extra stuff with my new weapon or troop, especially those two Arcanes!