It wouldn't do much if he moved faster than light?
Man, if Gladiator and spiderman are within fighting distance of each other, let's say, within 50 yards of each other(sufficient distance).
It takes a while to build up to lightspeed, according to laws of acceleration. So say Gladiator can probably reach between 20,000-80,000 mph from a 50 yard distance. The average human skeleton can take between 1,000-10,000 lbs of pressure(looked it up).Say spiderman's bones can take 10x this amount thats' between 10,000-100,000 lbs of pressure. If Gladiator reached between 20,000-80,000 mph with his 220+ lbs of body weight behind his fist. He wouldn't have to use his strength to cock his fist back and throw a punch, he could just fly with his fist straight out the whole time and still have enough force to tear spiderman's head from his shoulders easily.
"My spider sense is going..." "POWWWWWW!-cri-crackkkkkk"
[Gladiator has just flown in and knocked peter's head off.]