I'm going with a Blast out of Hands attack. -4 dice, but he's unlikely to get a defense roll because he is unaware. We'll use a regular shuriken for this. As an aside, are the stun shuriken re-usable after a recharge or battery replacement?
Simple: Ready shuriken
Simple: Throw Weapon
Blast out of Hands:
10d6t5 3 [5, 6, 1, 4, 4, 1, 3, 5, 2, 3]
Move: move adjacent to the person
If I'm lucky, he'll be surprised and I'll get the opportunity to finish him before he can act.