As of now, this item has no use other than for the Rukiryaxe Quest, or as a decoration. It also has a sand-like texture, slightly sticking out of the side of the bag
The description of the item was once "Time for Sand Castles." It changed sometime in the Beta Testing Stage.
It could be used just for decoration as sacks lying randomly around on the floor/base of a player, but it is recommended that you only buy when needed. There's a glitch where if you push two sandbags really hard into each other and reload the game the two sandbags can weld together.