User blog comment:RedBack 12/Here's something you might want to see.../@comment-27267198-20151130041729

 Wow I can't belive how many people saw this and responded!

But now that I'm all rested and have a clear head it's time for me to add my own two cents to why I think this is a big deal.

First of all, this is the enemy that gave her the scar over her left eye (here  you can see her without it at in the early part of the fight, then you can see it clearly in this transition), the reason I think this is such a big deal is because she kept that scar. Daughter of a rich CEO could easily ask for plastic surgery or something to remove it, and seeing how this is a resonable alteration to want it strikes me as odd that the didn't get it removed. Now there are a number of reasons she could have kept it, maybe it's too dangerous to operate that close to the eye, maybe it was to rebel against her father and of course maybe it was just a design choice to make her look cool (which it totally does). But I think the real reason she kept it has to do with the second point I'm going to make now.

Secondly, did anyone ever ask why and how she came to fight this thing? It always struck me as odd that all the other trailers were tied into the story somehow but this one seemed more like a concept battle. Not to mention the fact that nothing like this knight is seen anywhere else. Knowing all this and taking into consideration Winter's comment about "Fallen foes" I think that this knight was made and put against Weiss for the sole purpose of having her beat it so she could summon it later. They evidently made it as strong as they could while still allowing her beat it by herself so that it could act as a personal body guard when she needed it. And it's not like we havn't seen that Atlas has the technology to make something like that (assuming it works with robotic creatures and not just living ones or just Grimm).

Back to the scar point, I think she keeps it to remind her of the battle or to help her focus when she wants to summon it.

Finally I'd like to address the main point in the comments, Yes she has summoned this  sword before, but in this image (which I appologise I couldn't get a better quality picture of, but it was only on screen for about one second and we only got a good look at it for about 0.15) you can clearly see that it's just a block of ice in the shape of the Knight's Zweihander and there can be no doubt at this point that Weiss has no problem summoning and controlling ice, and the sword in the "summon" was more ghostly and looked like it was made of light.

(Man this was way longer than I thought it would be, maybe I should have taken it to the forum instead, maybe I will in a bit and bring all the information to one place)