While this doesn't couple with defense, these definitely should be considered. In particular, Icon of Unyielding Courage is very accessible and the usage is simple amazing with only a 2 minute cooldown to boot.
(This is about to go off on a Threat tangant...)
In terms of Rings:
Crystal Band of Valor (15 hit) vs Protector's Mark of the Redemption (15 BV)
Using the threat formula:
9.5-11 Hit Rating(0.6-0.7%) = 22.1 Crit Rating(1%) = 29 block value = 49 AP (out of Fortifications).
That formula has Crystal Band of Valor not only out threating Protector's Mark of the Redemption, but also Dath'Remar's Ring of Defense (39 BV).
LOL you know I've had Royal Cloak of Arathi Kings for a couple months and used it for dpsing on Aran and it never clicked with me that "Hey! 31 Stamina and 16 Hit Rating would be great for tanking too!"
That being said, I like to swap between Illhoof's cloak, Devilshark and the Badge one.