Ancient Dagger Up to 2.5k Years Old W Stars/Moons/Geometric Patterns Unearthed

I have a question. Who gets to own the dagger? The museum? Or the people who found it? What the general law around finding things like this and ownership?

In Poland everything found in the ground belongs to the nation treasury (government) and performing excavation in order to look for things like this is illegal without specific permit. So if you find something you either stash it and don't talk about it or it goes to museums.

it obviously depends on the laws of each country - in Italy, for example, if you happen to find underground an object of historical, artistic, or archeological value you have 24 hours to hand it to the authorities (cultural conservation institutions, municipal authorities or law enforcement). On the other hand, if you are using a metal detector you can't claim it's a random finding and you might incur in charges for abusive archaeological research. If the finding is indeed random you are entitled to a monetary prize by the state.

In other countries I would expect similar legislation

The laws are usually highly regional for things like this.

In some places it belongs to the government, in others the nearest historical authority, in others to you and/or with conditions. In others like Ireland its illegal, so not too long ago someone found two bronze age axe heads and mailed them in anonymously, creating the problem that their National Museum needed to know where the items were found.

In the UK you have to declare the item, and local museums are then allowed to bid a fair market price for it, which you have to accept. This money would then be split equally between the person who discovered the item and the landowner. It works pretty well - there's an incentive to legally declare what you've found, as you'll get paid for it, and by doing so the archaeology is often preserved and the item doesn't just disappear into a private collection.

Ref: https://en.wikipedia.org/wiki/Treasure_Act_1996

In a lot of places you'll get in trouble for digging things up because a huge part of the archeology is the objects location , context etc.

It belongs in a museum! "So do you!"