Better rethink the design on that one. A murine knife? thats going to both be really squelchy in a horrible kind of way, give out one last awful squeak, drive little tiny mouse bone fragments into your hand, that are almost certain to be laden with some sort of horrible infectious disease and spray mouse intestines backwards, all over the wielder. The consequences of an overhand stab would be, as a result, probably getting a stream of mouse/rat crap and instantly everted intestinal tract hitting you in the mouth and eyes in a disease-ridden, repulsively squelchtastic and slobbery, slimy not-quite-string-of-sausages-but-closer-than-you-want-to-even-think-about spray of rat guts sort of way.
I accidentally stepped on a dead rat once when I was younger, wearing heavy boots...and whilst I didn't check the heel of my newrocks for rat bone shrapnel, I both saw and heard the 'sphhhilcccnhhkkerrngnghhrrrhhpfftthttttrr' of a dead rat's intestinal canal plus various assorted internal organs coming squirting out of its ratty little anus and landing in a ropey, slimy, pallid, blueish-veiny stranded heap like a string of sausages might if it were whirled round one's head with a weight at one end then thrown. Only out of a deceased rodent's chocolate starfish.
Not a sight one forgets in a hurry. Fucking thing even squeaked. When it was already dead (before I stepped on its corpse) It didn't smell much better than it looked or sounded either.
So the handle on that gets squeezed? thats going to be a horrible mess, much of it pointed right back at the wielder of the rat-shiv.