Interesting key- there looks to be traces soft solder flashing where the stem meets the fluting at the base of the bow and also along the key-bit? Could simply be from a very poor repair, but could be because the key has been crudely made up from separate parts.
There’s always a story attached to items like this, and when it’s an antique dealer selling the taller and bigger the better- I would always aim on the side that it isn’t what they say it is, unless or until, it’s possible to prove otherwise. I’ve lost count of the number of huge locks and keys I’ve been shown accompanied by the words ’it’s from a castle…'
Realistically, I agree with the others- it’s more likely that it’s not from Neuschwanstein. Although the bit looks nicely made and the bow is interesting, to me it does have the look of the many ‘tourist souvenir’ keys that are out there.
Also I’d bear in mind that such a prized and protected site isn’t likely to allow contractors to just help themselves- I know that doesn’t mean that nothing (like your items) has ever left the custody of the site, but I would think it would take exceptional circumstances in the case of a site like Neuschwanstein. I used to fabricate a lot of bridge ward blanks and hand make the keys for a few of the prized Welsh castles- but I didn’t end up with toolboxes full of their locks! Restoration work is just that- preserving what’s there and keeping it working for future generations.
It’s a lovely key and it all sounds plausible but I’d take it all with a pinch of salt. It’s a shame all the locks were mislaid during a move- would have been great to have seen those as well.
