Not too strong or fast when Carnage and Venom can both blend into the environment becoming nearly invisible. It's not fool proof, but it does add to their deadliness. Both Venom and Carnage can take a hell of a beating. Carnage more-so. but can Arthur resist the symbiotes invasive assaults? There are two of them. If he can shut them down with is aquatic TP then it's a wrap, but he could be in trouble on a physical level.
Well It works a lot like the Predators. Like I said, it probably wouldn't be fool proof, but it could aid them if they attacked in hit and runs. Then there's the type of assaults that they bring to the fight. The symbiotes can be extremely invasive. It's his internal organs that would be in question if they were to attempt to gag him. Overall though, it may never come to that if he used his aquatic TP on them and it ended up frying them on the spot.
I wouldn't call Aquaman's piercing durability shitty. Sure he's more susceptible to being cut then most powerhouses, but he's also capable of taking machine gun fire with nothing more then scratches on his skin. That's less susceptible to piercing then powerhouses like Black Bolt or Wonder Woman who've been harmed by far less at a greater degree.
Not to knock them for it. Really depends on how strong of an item these guys can cut and how fatal that cut would be. As well as how often do they get those hits in.
One could argue that this way of acting is overall more exotic and unlikely to happen in a fight, but then I have seen people pulling those kind of strategies for their preferred characters lots of times if that was the only way to win.
All I can say if they would go for that it would work.