The Crystal Lance is a direct upgrade to the Spear.
Just like the first Spear, you can catch fish with it.
It radiates a faint glow similar to that of the Crystal Skull and Crystal Shield. It has the same move-set as the regular Spear, but deals increased damage over a slightly longer range.
You can find the Crystal Lance on Floor 20. (More information is needed here. Feel free to edit if you know how to get to it!)