I sorta wondered if in non mirror verse the tholians almost the part of self appointed time police while their mirror side where trying to make use of any temporal tech they could find. the tholians in the non mirror verse were more concerned with warning enterprise away. even then they allowed them to stay awhile to see if kirk would reappear. they didn't get pissed until the deadline was ended. even then their web seemed for containment and not destruction. as for the question of damage to defiant . a theory about connie shields is that they were like layers of an onion. multi hits would take out the outer layers while still protecting the ship. but they could feedback energy in waves .. where all the shaking of the ship came from. sometimes even with shields a shot might get through a weak point and cause an actual breach. but you could have internal damage in the ship w/o actual breach.