A little about Weiss as a whole:
They are a faction of four assassins who work for the mysterious "Persia." Their orders are given to them via videotape of Persia and the details are worked out later with Persia's assistant, Manx, and then later with Birman. If it isn't apparent as of yet, the members of Weiss and those associated all go by code names of cat breeds. The four members of Weiss kill for their own reasons, some better than others, but that's their business.
Weiss means "white" and can also be spelled "Weiß". But only if you're cool and know that 'alt 0223' makes the little ß symbol...