I know weapon balance doesn't need to be perfect, but I think the Vibro-axe seems a little strong for its base cost.
Not to mention the silliness that occur once you start adding mods.
With Brawn 3, you're looking at a base damage of 6(with pierce 2)
Now for a mere 1050 credits, you can add the Serrated and Monomolecular edge. Now you have a Crit rating of 1 and Vicious 4.
Seems like even moderately powerful opponents would be little threat if you managed to close with them and you were armed with a Vibro-axe with a few upgrades. You've then got beginner PCs punking nearly every enemy they come across instantly.
And if you've got 5000 credits to spend you can add the Superior quality for 1 extra Advantage, which all you need to trigger a crit(with +40 to the roll)