Hmm... dagger... must be used for dagging things... :^)
I recall looking up the word in my teens. A knife (at that time) was considered to have only one sharpened edge; a dagger and a sword had two, and the difference between the two was length, iow, arbitrary.
We’ve got a painting showing someone getting knighted, therefore, swords had only ceremonial purposes. ;^)
https://fineartamerica.com/featured/the-accolade-edmund-blair-leighton.html
Sometimes you just wanna get stabby.
Best,
L