it usually has enough shields to not give a fuck about any damage from small/medium ships
Shields have a cap so to speak.
I already have a weapon that can dent large ships and I have a small ship.
If 5M/s is the cap, im quite sure no small ship will "dent" it, if someone ever reaches it. It also works both ways. If you attack a large ship, you MIGHT dent it (people with large ships have as much thrust as small ones and can run to regen shields etc.), but if a large ships attacks you, you will be DENTED to hell and back, plus there are turrets which for another large ships are mostly a mere annoyance, but for small ships they are another thing to dodge and are actually threatening because for really large ships a single turret will be about as powerful as the small ship or more. At one point large ships have AMC lasers so fast and quick that they are hard to outmaneuver even by medium ships. Maybe small ones up to 50 mass or something, but i dont know your definition of small. If you have a ship made from 400 AMC's, 25 power, 1 core, 50 thrusters, 24 shields, you will maybe dent something, but normally people leave at least some walking space and not design their ship for pure firepower.
Honestly, in terms of size those classifications make no sense
To my knowledge there isn't even a need for size classifications in a world where there is nothing to distinguish the sizes except for size.
At least in naval and aeronautic classifications the sizes really did make a difference. You didn't make a carrier sized destroyer ship.
yea, actually the flexible class system is kinda nice!
I also kinda like the flexible system but still prefer the Blitzwing system