"Ares is weak!"
Okay, uh...? What makes you think that?
Is it because of his combat with Heracles, after the son of Alkmene killed Cycnus, the son of Ares?
Well, guess what? In most versions, Zeus throws a thunderbolt between them to avoid a fight, since he didn't want Heracles to die (yet, they still needed him alive so he could help them later in the war against the giants. They don't say this, but we can get an idea of it).
Is it because of his combat with Diomedes in the Iliad? Well, Diomedes only won because Athena had helped him. He literally ran away from him when he first saw him and only dared combat him when Athena showed up.
Is it because of his combat with Apollo in the first Olympics? Well, the other game described in this myth is a race between Hermes and Apollo, in which Apollo also wins. So we're comparing winning a race against Hermes (literally one of the, if not the fastest god) to winning a battle against Ares. That doesn't sound like they were calling him weak? But rather that it was, in fact, very difficult to win against Ares in a wrestling match, just like it was difficult to win against Hermes in a race, and Apollo did both so he was praised for it (I'm pretty sure he even got the epithet "champion" for that, but I couldn't check it because my internet is somewhat failing rn).
Is it because he lost to Athena? Bro, the whole point of Athena's birth myth is that she's powerful. Literally everyone else (expect Zeus) would lose to her.