Sorry, I am a historic military buff and I kind of get annoyed with improper usage of terms when it comes to weapons. GLA/PLD use round shields and tower shields and CNJ/THM use decorative bucklers and targes.

Shield Swipe is your hardest hitting move for the lowest amount of TP and it also blocks the enemy's weaponskills for 6 seconds every time you hit with it. Rage of Halone hits harder but in order to do so you have to combo it off of Savage Blade. At 46 you get Bulwark, a skill that increases your block chance by 60% for 15 seconds so you could be able to use a tower rather effectively and still proc swipe in a long battle. If you already have a high block rate, say 150 you are already blocking a lot. Using Bulwark would increase it to 240 a whopping 90 point increase. Use it when you need to burn through a boss with a round shield and you will basically just be shield swiping for 15 seconds. At that point you won't need the threat from your Halone combo anyways.