Can be anything from any source, movies, books, comics, video games, manga, anime etc.
Pic related is mine, the dragonslayer from berserk. I like it because it's simple. It's just a big fucking sword, no fancy bells and whistles like enchantments or spells.
Second runner-up is sting from lord of the rings, I like that it glows blue when orcs are around and it can be used in the dark as a light source.
side note but I really enjoyed how the character raelza in this handyman saitou anime has a similar sword to Guts's but it shows a slot on it/her armor that she locks it onto and it's like, nice, they actually show that instead of the sword just being stuck to their back like a magnet
Guts has a kind of like chain sheath for the dragonslayer but you never really get to see how it works
yeah that's why I really appreciated seeing her slot her sword in, just like a really small detail that I thought was cool