The numbers quoted suggest 11.4% ABV, so unless you used something as "light weight" as Wyeast sweet mead yeast (tolerance quoted at 11% ABV), then there's still probably room for it to ferment further. Little to be gained from trying to kill off the yeast etc.
Just let it finish, then rack it, stabilise it and then back sweeten - I use a 50/50 honey and water mix. I make it up, take a reading, then add about 50 mls per gallon, gently stir, then test again to see the gravity, most of the test goes back into the batch but I taste a little.
That way I can repeat it for higher gravity, I learn roughly what I like my mead at (at leas for that brew), numbers-wise and I know when to stop adding more honey mix for the back sweeten.