Consider the Phoenix Shield the better version of the Bulwark and Impervious that T4 non-heroes can use. That is why it is red and the other two are orange.
For people curious about shields, 100 HP is slightly better than 2 armour based on previous testing. The shields of this game have tried to keep to that rule in balancing. Most of our enemies deal cut damage and follow this rule. There are a few that do blunt or pierce, but they rare enough and already do low enough damage that it doesn't particularly matter. Even then, the HP shields don't get too far above of the curve, taking an astounding 2-3 hits extra.
For people curious about shields, 100 HP is slightly better than 2 armour based on previous testing. The shields of this game have tried to keep to that rule in balancing. Most of our enemies deal cut damage and follow this rule. There are a few that do blunt or pierce, but they rare enough and already do low enough damage that it doesn't particularly matter. Even then, the HP shields don't get too far above of the curve, taking an astounding 2-3 hits extra.