The G2 Laser Rods have the same gimmick as Micron Legend Hot Rod and Masterpiece Grimlock -- an LED which illuminates the sword. With Laser Optimus Prime the LED also illuminated the headlights in truck mode. The Laser Rods were pretty neat and were among the very first generation of Transformers with highly articulated and poseable robot modes. IMO Laser Optimus Prime was an extraordinarily well crafted toy for its time and arguably one of the best Optimus Prime toys ever designed.

Canonically they wield energy blades - which is nothing new to Transformers - after all there were several G1 Transformers who wielded melee energy weapons such as the energo-swords wielded by Grimlock, Slag, Sludge and Snarl (but not Swoop - his weapon is a thermal sword). The LED piping looks cooler than just bright red plastic.