To perform this, find any Elite, in any mission, on any difficulty. Without inflicting any damage on the Elite, assassinate and proceed to shoot his corpse. It should flicker, as though the Elite's shield were still functioning.
The easiest way to perform this glitch is to start Assault on the Control Room, and play until you get to the bridge. There is an Elite on the lower level. Simply catch him off guard, assassinate him, and shoot his corpse. Another way is on The Pillar of Autumn after fighting through the cafeteria there is a hall with an Elite facing away. Simply assassinate him and shoot. His shield will still be up.