Visionaries was a cartoon from the 80's which only ran for 13 episodes, which is why i guess it isnt very well known. In the series there was a group of knights of the spectral light (good guys) and darkling lords (bad guys). A wizard named Merklyn granted them special powers which they could access by saying a special poem. These powers were represented with a hologram on their weapon/shield and their chestplate. the chestplate power could enable them to change their form, and the one on their weapon was a super powerful weapon. Once they used their power, it had to be replenished by merklyn - who had them doing errands/missions.
My mind is a bit hazy - havent watched the cartoon in a long time