[quote=@Nytem4re]
<Snipped quote by Lmpkio>

I think it's just that it seems highly irregular for a clone to use. They probably were never trained in melee combat with a sword, as they had a firearm and rifle. That's my two cents. 
[/quote]

Good point. But like I said, the Commando simply found it and decided to keep it as a "souvenir" so to say. He then was in a pinch and he used it. But he won't use it too often, for he'd mostly use his firearms and detonators to keep the jedi at bay. He'd just use it in case he's left with no choice.