Sumalis was a desolate, dangerous wasteland even before the desert became a magical ocean of sand populated by undead and people avoiding civilization.
Eight Anchor Cities exist in the region, and aside from a few coastal villages, they are the only populated areas that don’t move with the currents of sand. Numerous settlements, encampments, castles, and towers, all of which (both populated and not) exist out here in a constant state of smooth and barely noticed movement, carried along by the whimsy of the sands.
The sand currents follow a semi-predictable pattern of swirling around the Maelstrom that allows skilled navigators to fairly predictably chart a course through the desert as well as track things like settlement locations. The Maelstrom is entirely uncharted, as the sands move faster and become harder and harder to traverse the closer one gets to it. An area hundreds of miles across is in a constant swirling sandstorm, rendering visibility nearly impossible outside magical means.
So. Venture a couple days out into a magical sand ocean, retrieve a deadly weapon, and bring it back to where it can be safely cataloged, studied, and stored. How hard can that be to a group of fine adventurers like yourselves?