When you enter the sanctuary, the ideal place is the first engagement after unlocking the shortcut and going into the courtyard with a heavy and two grunts. Take out the heavy and a grunt and lure the other grunt down the steps to the left overlooking the view. You can use Focus Eye Poke to stun then and grab and throw them toward the ledge. If you’re close enough, it will throw them overboard- too far away and they will be thrown against it. Otherwise, you can damage their structure or parry then grab to achieve the same effect.