A Japanese magazine revealed that Zelda would deploy Light Arrows for her Final Smash earlier this month, but today's dojo update is still worth a skim for those in search of greater detail, not to mention new screens of the move in action.
You only get to fire a single Light Arrow as part of this Final Smash, so missing isn't the best idea (Sakurai hints that the Arrow will be easier to dodge in a one-on-one match). The good news is you can fire your precious projectile as either Zelda or Sheik, with some aspects of the attack (such as the direction your opponent gets knocked in) changing, depending on who is used.
One thing is true of both fighters, however: the Light Arrow packs some real punch if it does find its target. As Sakurai puts it, once characters are hit, they're "pretty much done for." Anyone tempted to give Zelda a whirl in Brawl?