You can choose to use shield spell 1, 2 or 3(hotkey them), once you use one, you'll get one of the three effects at random.
To figure out if which SS3 you got, just check if your def increased or if you healed yourself, if nothing happens but you still have the icon, you got the armor breaking SS.
Once you figure out which one is the armor breaking one, check the timer duration on the shield spell icon as it will be longer than the timer for the increased def.
Remember that the shield will affect the duration of the skill so if you memorize the time(to make sure is armor breaking ss3) use the same shield.
This way is easier than keeping your info window open to see if def increased or not and you just have to hover the mouse over the SS icon to see the timer.
Edited by Aizenath, 06 September 2016 - 04:19 AM.