User blog comment:Xilinoc/Ch. 571 (Yachiru's gonna wreck it)/@comment-10205398-20140305152727/@comment-1268838-20140305154154

I am pretty sure that the first explanation is more correct - both uses of its ability in this chapter seems to suggest it. One attack hits before, and one hits after. If it were the latter I think that all three attacks would hit simultaneously, which while useful, wouldn't have worked against Guenael. The blades wouldn't really hit Yachiru herself, because from the looks of it, they are always parallel to her own sword, and follow its exact path. Their arms and blades would never touch.

So it's indeed similar in principle to Tenken, but it doesn't really increase the range or scope of her attacks. Rather, it increases their margin of error, while making direct attacks three times as powerful. There's also the fact that the ability is apparently invisible to the naked eye by default, so it's kind of ironic that Yachiru would give away that advantage by revealing it.