i really really love the magical muskets for a really specific reason, which is that blackpowder guns are way older than people think and should 100% be treated with similar mythological weight to swords and spears and stuff at this point, and they should have equal prominence in generic fantasy fiction stuff.
lemme put it this way; european longswords and european cannons are siblings. they emerged at basically the same time in the early 1300s, and when the longsword was at its peak use in the mid-1400s, the musket was beginning to proliferate.
likewise, the 'modern' style of katana only started being made in the century leading up to the introduction of muskets to Japan; in fact, the reason the katana became The Samurai Sword was because it was a small practical blade you could wear while you carried a gun.
if you can picture your setting having a sword you can use with two hands, then you should have hand cannons. if your knights have full plate, then there should be matchlocks. if you have a magical girl with a sabre, then you should have magical girls with flintlocks.