Sumatran Sewar?

[David]

So this is a little outside my usual sphere of collecting, but i was in my favorite antique shop in Halifax, NS and the owner was just unpacking some new items he picked up at a recent estate sale. I once found a worn, but interesting anak alang keris there for a good price and we were chatting about that and he remembered this dagger and pulled it out to show me.
Well. i though this thing was just so damned cute and the price seemed rather good to me (though again, out of my collecting sphere so i can't be certain, but i think i got a great deal on it) that i just had to bring it home.
My understanding is that this is a sewar, but that that these blades are also referred to as Sewah by the Gayo people, Seiva by the Minangkabau people, Siva by the Alas people, and Siwaih by the Acehnese people.
I have know idea which region or people this particular one comes from so perhaps someone out there who knows more about these can help me out nailing down the identification and possible age.
The sheath seems to be horn and the fittings are sliver. The blade length is about 22cm (about 8.6 inches), about 28cm (11 inches) including the hilt.
The blade is pattern welded and seems fairly old. A stain would raise the pattern, but i am not certain that these blades were traditional treated with warangan or not so perhaps someone could advise me about that. Thanks!