Thought this was going to be useful to get trolls roar pre mountaintops by duplicating off trolls hammer. It makes sense that unique ashes can’t be duplicated but, annoyingly enough, it can’t duplicate normal ashes off weapons either.

There is literally no reason to use this item.

Can you later remove a duplicated ash of war from your inventory? Or will you have two of the same there forever?

Does duplication work for Ashes you find on quests like Rogier’s Rapier and Edgar’s Banished Knight Halberd?

There's an unlisted one in Leyndell slums' sewer tunnels (not Subterranean Shunning-Grounds). Past some rats and small hand enemies, at the end of a long straight otherwise empty tunnel that has the Lost Ashes of War and a wall-clung large hand enemy guarding it.

Anyone have a number of the total Lost Ash of War in the game?

Unique ashes of war cannot be dublicated.

I have 15 of them

So am I trippin or are these things next to pointless? It honestly makes me feel like at some point in development, putting ash on a weapon was supposed to be much bigger deal than it ended up being in the release version. Like the ashes were probably one time use, would get soulbound to a weapon and this could be used to have an extra copy in case you wanted to put it on another weapon.
Imo you are effectively hurting yourself by running two or more of the same ash, even on weapons you switch between. I think its way better to have different ashes ready for different situations. Honestly the only use I can think of is to have two of ash that buff the weapons themselves (determiantion, seppuku etc) for maximum possible damage meme builds or if you are a sweaty tryhard and just want to run bloodhound step on everything.