BlazBlue: Cross Tag Battle is a fighting mashup of four different franchises. BlazBlue, Persona 4 (Arena), Under Night In-Birth, and RWBY are all represented here. When Cross Tag Battle was initially announced, RWBY’s inclusion was arguably the most surprising inclusion.
Monty Oum was a fan of BlazBlue. Mori is a fan of RWBY. The fact that Central Fiction had palette swaps based off of RWBY characters both shows that and it was a nice tribute, but Ruby clashing with Ragna the Bloodedge is beyond awesome. ArcSys really wants to pay their respects.
RWBY has been noted as taking several cues from Arc System Works games, be it through story elements or just blatant references. Now Ruby is in an Arc System Works fighting game, and her Japanese voice actress even voices one respective character in two of the featured crossed-over series.