This is the officially licensed Legend Of Zelda: Seal The Darkness Master Sword Light (instead of magical sword in rock light) available for pre-order from Merchoid ($43, shipping in August). The USB or 3 AA battery powered light looks like the Master Sword in a stone (the triforce symbol is the on/off button) and emits a soft blue glow from the top of the base. Granted that doesn't really look like enough light to comfortably read using unless you already have partial cat-vision, but it may be enough to convince yourself it'll keep the monsters at bay. Me? I've never believed in monsters hiding in my closet or under my bed because I'm not an idiot. It's the ghosts and shadow people you really have to worry about.
Keep going for a handful more product shots.
Thanks to Julian ET, who agrees for being so dangerous to go alone you think the old man in the cave could have provided a better sword.