The Fusion Sword is a sword that has orange energy on it and lines like the Cosmic Monolith.
In Epic Battle Fantasy 4, it is a massive, bulky blade resembling a giant Bowie knife. It has three small openings along the cutting edge of the blade, revealing orange-glowing energy or radioactive material within. These openings are connected to intricate designs on the flat of the blade that resemble patterns on a circuit board. The hilt is barely distinguishable from the blade, but appears to incorporate a small fusion reactor (hence the sword's name), wires, and a pair of tubes/exhaust pipes. The cross-guard is small and nondescript.
In Epic Battle Fantasy 5, it received a massive redesign. It was made more slick and smaller, and now resembles a sword more than a giant Bowie knife. The blade was made to be more separated from the cross-guard, and it was also is now black. It also has a noticeable fan on the side of the cross-guard.