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.
“Here is my sword,” said Intra. “Your semiotics cannot contain it. Its blade is made of gloaming steel, look how it whispers!”
“But Lord Intra,” said the assembled, “You have no sword!”
“So it is,” said Intra.
-Psalms
(text taken from Kill Six Billion Demons lore)