i actually have macros for each seal i use one for vengeance and the other for command
/cast Seal of Vengeance
/equip Libram of Valiance http://www.wowhead.com/item=47661
/cast Seal of Command
/equip Libram of the Eternal Tower http://www.wowhead.com/item=50461
so if a boss fight i have to switch from tanking adds to tanking the boss or something like onxyia i don't have to search in my bag and change out librams and librams ARE considered weapons so you can change them in combat.
I am actually older then your jesus i wish i could of known him....but i missed it. Godrick True Blood