User blog comment:Azurebluecyan/Aura Strikes/@comment-3257939-20151028000335

The thing that caught my attention the most was the images of the food fight and Ren's fight against the King Taijitu. From what we've seen, it's the exactly same thing. Since they're using food, they have to use Aura to add endurance to the food in order to properly use it as a weapon. I believe this is exactly the same thing Ren did in the Emerald Forest. He used his Aura in his hand to transform these into weapons that could tear through the Grimm's flesh.

If that's the case then what we saw in there wasn't his Semblance at all. Not confirmed but this blog serves as a major point for that idea.