Blaster-Tron isn’t just state-of-the-art technology; he literally is from the future.
When the Skylanders traveled forward in time to stop Wolfgang, they ended up bringing back the renegade robot with hopes that they could learn from his advanced circuitry. Eon immediately noticed that he had an actual “Good/Evil” switch that had been set to Evil. After flipping it to Good, Blaster-Tron was completely transformed. Besides going from bad robot to good robot, he ditched his blaster gun in exchange for a laser sword. No one knew exactly why, but as long as he was helping out the cause of justice, the Skylanders were happy. As a bonus, Master Eon noticed that his skill with the blade was second to none, and so he made Blaster-Tron a Sensei for the Knight Class, where he now gives 110% to training his students - which is technically possible because in the future, we figure out how to give more than 100%.