Also, anthro (furry) characters. The assailant is a mouse, and is roughly comparable to a skinny and short (though both are in reasonable ranges) adult human male. Victim is a crocodile, and is taller but very unhealthily emaciated--words to describe him at this point include "skeletal," "lich[like]," and "patches of scaly hide [hanging] off bones, with just enough room beneath for internal organs, if even that." (Note that some hyperbole may be involved here for dramatic effect, since he is obviously still alive without necromancy involved--no magic in this setting. Though he might not be for much longer in the kind of shape he's in.)
Research: Googling medical stuff on the severity of stab wounds in various locations, also used the tags and looked back through previous questions in this very community I thought might be relevant.
Question: The mouse and crocodile fight and the mouse stabs the crocodile once or twice. The knife is substantial (Bowie sized, probably, but can be cahnged depending on what works best) but the mouse's limited strength might be a somewhat mitigating factor, depending.
Anyway, what I need to have happen is have a wound that won't kill immediately, but is unavoidably fatal given their lack of access to medical attention. The fight ends with the mouse victorious, but he doesn't want to finish off the crocodile, only for the crocodile to remind him that he pretty much already did, given the inevitability of infection even if he doesn't just bleed out. I need the crocodile to be a goner but still have time to have a fairly long farewell conciliation and separation (either the crocodile hobbles off to go die somewhere or just talks the mouse into leaving him) so that he can be left with a heavily-implied offscreen death, possibly by suicide just because it beats waiting for the infection and such, but whatever works/makes sense in context.
In the current draft, he gets it twice from behind, once in the back of his upper right thigh and once in the upper near-base area of his tail, but I'm probably going to change that because it seems a little underwhelming for "yep, I'm totally going to die from these and there's nothing that can be done about it now" purposes. Bonus points if it's something that gets him somewhere from behind (again, current version is back of thigh and tail) as the choreography of the fight is just more convenient that way. One of the sites I found seemed to imply that lower back might work, but I may as well check with you guys.