Namor can't fly as fast as a herald of galactus and Spidey lost firelord. namor can't shoot anything either as far as I know and spidey can dodge a thrown projectile with great ease. Firelord isn't as strong physically as namor but he's much stronger than spidey and when spidey went all out on him he was unconscious before he could even think of increasing his temperature so spidey couldn't touch him. That's one fast a** whippin and if the avengers hadn't have stopped him he might have killed him. Spider-man usually beats himself trying not to do to much damage to his foes. give him the bloodlust of the symbiote suit
(which only effects his webbing not any of his other powers) and namor is dead not just beaten.