Vulcan, or the Infinity Sword, started as a mod for Ultima 7 on Exult. It was intended originally as a sword counterpart to the Infinity Bow from Serpent Isle and as such followed its black and red color scheme.
Below is the 2d sprite I made for the game, from which the core design of the sword originated.
I later created, in Photoshop, a digital drawing of the sword. In this more detailed rendering of the weapon I designed its bat-like crosspiece and the dragon claw pommel.
Using the digital drawing for reference, I translated the sword into 3d as part of an unreleased mod for The Elder Scrolls IV: Oblivion. The image below is of the Sykrim version, however it's the same mesh, just the textures and UVs were reworked for the game.
Finally, we arrive at the Infinity Sword's current form as Vulcan, which was made for EverQuest II. I had to make a completely new mesh in order for it to fit with EverQuest II's requirements, which resulted in the sword's design taking on a much rougher, more volcanic appearance. Vulcan was accepted by SOE's Player Studio and is available through the Marketplace.