Few ideas and thoughts:
Current sterling crystal chest, wonder chest and pet chest are fine as is
Remove old soul shields and replace them with updated soul shields (BM / Poharan / True Poharan) at a discount. Ability to purchase specified pieces would be amazing
Add different upgrade materials (for example, fusion stones, skystealer crystals, starcross stone fragments, upsurge essences etc. Currency used could be demonsbane challenge tokens. Or then just make these a weekly box for solar energies / honing oils)
A weekly chest that contains materials for weapon amulets (Silversteel Anima / Twisted Fury). These are hard to come by especially for newer players so making these more available wouldn't hurt
Perhaps a source of higher quality (searing+) etching stones.