Faster Cast Rate does reduce this delay, but at only half the effectiveness. Melee characters will be unable to attack during this time. However, be aware that when triggering Firestorm, it will cause a cast animation, resulting in a delay of 0.6 seconds. The -28% fire resist is also useful for characters who specialize in fire damage.
Phoenix is the only way to get enhanced damage on a shield (aside from +x% enhanced damage jewels), and the redemption aura is very helpful in keeping the character alive. 1.10–current Phoenix is the rune word ' Vex Vex Lo Jah' for weapons or off-hand armor in Diablo II: Lord of Destruction.