Aren't stabs in the lower abdomen usually non-lethal, though?

I mean, it must hurt like fuckin' hell and blood loss is a big concern, but I doubt they'd kill off Weiss like this, even if this is Rooster Teeth we're talking about here.

On a medical level this wound is easy to deal with.The blade is obviously one of Cinder's (Insert joke about Cinder targeting Jaune's love interests here) If so we can speculate that the weapon is extremely hot. If that is the case, the wound would not bleed because it would have been cauterized preventing massive bleeding. However, unless treated right away, the burned tissue would prove to be fatal as infection sets in.