Wuss is a tricky one.
The word pronounced (usually) to rhyme with puss is widely used, but it's so new (1976 is the earliest example I've been able to find) that its spelling hasn't had time to get properly established.
This means that although we all know what wuss is (a coward and a weakling) we can't be certain about wus.
Is a wus the same as a wuss?
And what about if someone is saying the word out loud? You can't hear the spelling, then, can you.
In most of the world, addressing someone with the words open the door, wus, is likely to get you into a lot of trouble (though not if the person you're speaking to really is a wuss. In that case he won't dare do anything about it.).
But if you're in South Wales you'll be fine, because in South Wales the word wus means more or less the same as mate.
So what can we do?
...if anyone calls us a wuss, pretend to be Welsh?
That's the wuss's way out, in any case.
Thing To Do Today But Perhaps Only In Wales: be a wus(s). The originally American wuss might be short for pussy-wussy, possibly with a bit of wimp thrown in. The Welsh English wus comes from the Welsh was, which is a form of gwas, servant.