Weapons in TF2 have the concept of attributes which control how they behave. We have the ability to add/remove attribs from any weapons, in addition to entirely replacing weapons with different ones.
Check this site for a list of attribs.
That is a REALLY useful list to go by. I wish it were posted in the first place.
Anyway adding #224 to the cleaner's carbine seems legit. Since a lot of bushwacka jumping snipers end up at half health anyway, it'd be cool if the carbine had the equalizer effect.
Although it might lean towards being overpowered and I think the snipers need a more defensive buff if anything. :/
Perhaps give it to the baby face basher? It would kinda give scouts a reason to use the atomizer/boston basher/three rune blade.
I'm just throwing out ideas as I go along.