1. Esdeath surprised the Wave, and he was never prepared. She's also very strong (knocked out Tatsumi in one blow), was able to keep up with Suu and Tatsumi with ease. Run is also pretty fast himself, and was complimented by Esdeath.
2. Susano'O's punch was able to kill a normal human being with one blow. I don't see how that is embarrassing.
3. It's not an accomplishment if you hide in water, while invisible.
You can try to justify those cases and I agree, but that doesn't change the fact that Wave's fighting skill seemed poor to people until he actually started fighting seriously. I mean, I could justify the Syura cases, too.
1. Much like in Suu case, Wave just had more physical strength than Syura and was over-all, a bit better in a close combat without Teigu usage.
2. Much like in Tatsumi case, Tatsumi used his invisibility that the enemy didn't have info on which made the enemy hesistate for a second so he could escape/kick them away, but just because he tricked Syura/Wave doesn't mean they are weak or would lose to him in direct combat.
3. Much like in Esdeath case, Syura didn't expect Budo to attack him at all and had his eyes closed.
Just like with Wave, people are getting the impression that Syura's fighting skill is poor, even though that isn't true in either Wave's or Syura's case.