Salthorae
Imperial Mountain Dew Taster
Why train people to use swords and expensive equipment if fists are just as deadly.
Well, they're not reliably so unless you... train with them. So you're training either way. Realistically's harder/more time consuming to train someone to be deadly with their body than to put armor on someone to protect them and tell them to stick the pointy end in someone else wearing armor (which is how most conscript armies work(ed)).
Even then they're not AS deadly as evidenced by the d4 for damage that both Tavern Brawler and Monk start out with... equivalent to a dagger. While a Barbarian or Fighter can start with 1d12 or 2d6 damage.
Also, and I know I keep referring back to it, but a trained & lifelong martial artist's advice (Jackie Chan) in the video I referenced earlier, is to run from a knife-wielder if you can and you're unarmed yourself. So... there's that.