Having gotten more into playing a hybrid build I often take Aegis and Guardian on my bar. I've read comments that Guardian is redundant if you have Aegis, but I like having Guardian to toss around while Aegis is recharging.
I'm just wondering about something... often a party member gets focused on by monsters and even under Aegis the health bar starts to go down quicker than I like, so I'll put Guardian on them even while Aegis is up. I've been thinking that the chance to block is calculated for both separately giving better protection. It seems too, but I'm wondering if that's actually the case.