Should WHM get a personal damage buff?

[Seraphor]

5 minute duration and 10 second CD? So basically free mitigation forever?

As opposed to the 30m duration, 3s cooldown it currently is?
It's actually a reduction in duration, making it a little more 'hands on' so it's only fair that it gets a very slight buff, for all those who might not notice it dropping off.

Because they're mutually exclusive, you either have Protect OR Shell, you can only mitigate half of all damage, on average, making it an effective 5% damage mitigation.
Compared to current Protect which is roughly 3% of all damage (more if you're overgeared, less if you're undergeared, maybe a 2%-6% range because you're not going to be THAT undergeared) that's not much of a difference.
In addition, you could just stick out a Protect and not bother with Shell, if you weren't playing optimally, and if you happened to be fighting enemies who deal a lot of Magical damage, then your effective mitigation drops below that 5%.