Well, this is a match for your beast, a silver gilt enamel Russian dagger/letter opener. As to what its era was, it's hard to say, really--there are a few of them on sites like eBay and small dealers, but they give no details, and prices are suggestive of replicas. One says outright that it's a reproduction. This doesn't mean yours is a repro, but it points in that direction pretty strongly.

As you know, it’s a letter opener. The blades of letter openers are often made of softer metals such as silver or bronze ^[1], not simply because softer metals are easier to work, but because slicing open folded paper is better left to a dull blade that won’t damage the letter. The sharp tip suggests it’s a letter opener, not a paper knife. Paper knives (with rounded tips) were common around the turn of the 19th century, when books and pamphlets often had uncut pages. By the turn of the 20th century, books were usually trimmed before sale, but the rise of mass produced envelopes made letter openers useful. ^[2]^[3]

Letter openers didn’t become popular as souvenirs and gifts until around 1900. ^[4]

The enamel work is generally called Cloisonné, though it’s a mass produced item using machine stamping and more properly called Champlevé. ^[5]

The Byzantine double headed eagle is generally associated with Russia, as it appeared in the coat of arms from circa 1500 until the Bolshevik Revolution of 1917. ^[6]

I can’t tell you when or where it was made; the fact that it’s from Finland makes me think it really was produced in Russia. If I had to guess for a time, I’d think 1900 to 1917, when Russia had the technology and factories and materials. And during that period, Russian arts and architecture were sort of a mishmash. Sometimes called Russian Style Moderne, it was a mixture of art nouveau, and a neoclassical revival that pushed back against art nouveau, and a revival of Russian folk art. ^[7] ^[8]

Of course, as a mass produced item, it could very well have been in production for 100 years, could still be in production today. You can find dozens of similar items, with a wide range of color variations, by googling terms such as "eagle peacock cloisonne enamel letter opener” or “brass enamel knife” or “russian letter opener.”

Sorry but it is just a fancy letter opener. The sort of thing sold to tourists. There seem enough of them around, that they were either very common vintage item and possibly still being produced today to sell to the tourists.
It might be Russian, but the craftsmanship is not that good I would suspect Greek (if vintage) or (if modern) China or India.
http://picclick.ca/Russia-vintage-enameled-brass-cloisonne-knife-dagger-w-Byzantine-262721797161.html
https://www.etsy.com/listing/486500359/antique-greek-bronze-and-enamel-letter?utm_campaign=shopping_us_prestigiousantiques_sfc_osa&utm_medium=cpc&utm_source=google&utm_custom1=0&utm_content=10372740&gclid=CjwKEAiAoaXFBRCNhautiPvnqzoSJABzHd6hetaqcHQ8scnvL1frXzY7F8FUlMJ2bOT9dRE48UTAehoCvjjw_wcB

Thanks for the replies /u/khosikulu and /u/PKDickman

I made some research now that I know what this is and found out that the new ones are being sold for 119£. Mine just seems to be a bit different and older. Thanks for sources!

EDIT: I checked and there's none for sell on the internet as they are being sold out very quickly with price ranging from 120 euros to 150 euros. Any suggestions what I should do with this?