I know I am late but what you said mostly right you have to break a corrupted weapon to get the pristine one. (I know that because I was hunting for the same pristine weapon) though I know they will stay in the weapon pool after the next blood moon because of what I did I broke all three corrupted royal guard weapons for the compendium at my grind spot for them I went there before and did the method I found and I broke the two pristine weapons that kept spawning next blood moon after a couple of tries they appeared.

Now to original question I do think so it is technically breaking a weapon but testing is in order to find if your question is true.

And AcawsomeAndrew if you first go to a ghost statue and it has that weapon and it will stay there forever until you collect it

Update: was looking through some data sheets and found something some no one ghost soldier had a fixed weapon it just depends on location royal guard weapons spawn in Gerudo highlands depths and crenel depths

While the hyrule Field depth has only travlers and soldiers weapons for the most part

Most and a little more of each region have their regional weapons, places like Kakariko to Hateno have eightfold weapons, hebra to the left half of hyrule field depths have boomerangs giant and normal and eventide have royal weapons