Not only did they sell a massive number of potions, they were also cleared out of accessories.
Weapons were much more common drops, but specific accessories were almost impossible to get from a Dungeon, where the stats on the very few that dropped were random, and rarely perfectly matched to any class and specialty.
So, even if they were Commander and Royal Rank, the ones that were sold by the Darklight Host were still an upgrade for basically all the Alliance members Overlord Rank and under.
For the stronger members, even one Stat in their category was enough to make it better than anything at the Royal Rank. However, the Guild Leaders had hopes that Karl would soon put a few items at higher Ranks up for sale.
Ashbringer's Overlord Ranked weapons had sold very well, though they weren't all gone yet. But when Karl put up a dozen Overlord Ranked rings for warriors, they were gone faster than anyone could feasibly have read the full description.
