Retractable Blade AOE?

Hi people,

I just rerolled my Mercenary/Scoundrel as a Powertech/Scoundrel, as the dual pistols weren't really my thing. I've never really played Powertech beyond level 10 for some testing, and I just got Rectable Blade on my level 15 Advanced Prototype toon. I'm loving the ability, but I notice that it will sometimes damage all enemies around the initial target. This is not consistent at all, and it happens only about half the time.

I've been playing SWTOR since launch, but I'm not an MMO person in general. Still, this is the first time I've been unable to find out what exactly is causing an ability's effect. I know there's a passive you can pick later which allows the bleeding refresh to damage multiple enemies around the initial target, but I don't have that yet.

If anybody could tell me what's happening here, it'd be much appreciated!