We know that the "God Metals" in Mistborn are investiture from Shards in physical form. We also know that Shardblades are Spren, which are basically sentient investiture, manifesting in the physical realm. So if one were to bring a Shardblade to Scadrial (the world where Mistborn takes place), would it be able to be used for the three Metallic Arts with unique effects?
To answer the question in the title, Shardblades are definitely god metals.
We know that Shardblades are god metals:
Brandon Sanderson: I also got confirmed that the metal that spren turn into is god metal.
And, further, that god metals of all the Shards on Roshar are possible.
yulerule: Written: If an Allomancer Worldhopper really wanted to hack the magic system and knew what they were doing, could they get their hands on some tanavastium, rayseium, or egdlium? Basically make god metals from the other Shards?
Brandon Sanderson: Reading question: If an Allomancer worldhopper really wanted to hack the magic system.. mumble
Uh, yes. This is possible.
So it seems fair to assume that the Shardblades are basically made of an alloy of tanavastium and "Cultivanium" (we don't know Cultivation's Vessel's real name yet), with proportions depending on the spren.
Now, we know that at least one other god metal, when present on Scadrial, allows for some unique effects: the so-called Trellium seen in the second Mistborn series, which is definitely not one of the mundane 16 or some combination of Harmony's essences, and is associated with some other entity, almost certainly a Shard. When used as a spike by Kandra, its effects are entirely different from any known previously. It's pretty reasonable to expect it to do some odd things when used in Allomancy and Feruchemy, too.
As such, I think we could expect shardblades to be usable for the Metallic Arts.
That said, there's a big caveat. Shardblades are not pure Physical Investiture, the way that Atium is. They're alive, since they're a manifested form of spren, and also Invested. We know they'd resist Pushing and Pulling, for that reason. As such, I would expect them to resist attempts at burning, and possibly Feruchemical modification as well. And there's almost no doubt that successfully burning a Shardblade would kill the spren that composed it. It's possible that a smaller portion could be separated off of the spren without killing it, though.