This is an officially licensed Game of Thrones replica made by Valryian Steel.
You can ruin seven seasons of intricately wrought plot lines and indeed the entire catchphrase of a show with one blow from this, so be careful with it.
This dagger is 19 1/2" overall with a 10" stainless steel blade (enchanted to kill White Walkers, really) and a faux dragon bone grip with 24k gold plated fittings. It comes with its own wood stand with an inlayed map of Westeros and a protective acrylic dome.
Each limited production Valyrian Steel (tm) replica is individually serialized with a certificate of authenticity.