Brass Dagger ceremonial decorative.

Hi.
I bought this brass dagger from a car boot sale in England about 15 years ago.
I thought it was some sort of Sikh ceremonial thing worn at weddings and the likes but after contacting a Sikh, he told me that it was more likely to be European dur to the two headed Eagle.
I'm not convinced though as the two headed eagle appears in indian culture and the knife also features a Peacock.
I would love to know it's origin, purpose & value. I paid £2.50 for it.
It really is beautiful.
Thanks in advance.
Alan.. 

Good