It's not a successor of Apollo. Perseus is. Myrmidon is actually a predecessor of Erinyes.
It's a light assault fighter and it's true purpose is to raid convoys, supply depots, cripple cruisers and disarm/disable things. It can dogfight, but does not do it well due to badly-placed guns and thicc ass. Loads quite a lot of missiles, loads Stiletto, loads Treb, 4+2 gun banks are perfect for Kayser/Prom S + Akheton. The game simply mislabels it as space superiority tho.
I think when one starts to use it not as a space superiority but lighter assault, Myrm is a good fighter. I think it's much better then the popular opinion suggests. Tho there is nothing that Myrmidon do, that Erinyes cannot do better... Except compatibility with Helios :].