Ogre Mages are smart how? Think up a good background, and I'd honestly be fine with it. Generally speaking, Ogres in FfH are about as intelligent as a stump. Were these exposed to a blast of Mind or Chaos magic? That would be a decent explanation, rather than simply saying "These ones are intelligent, deal with it."
Seeing as FfH itself was based on D&D (just say no to WoW)
http://en.wikipedia.org/wiki/Ogre_(Dungeons_&_Dragons)
In the Dungeons & Dragons role-playing game, ogres are a lesser race of giants, rather being simply large brutes with clubs. An aquatic subrace of ogres is known as "merrow." D&D ogres are also closely related to the race of ogre magi, a smarter race with blue skin and great magical abilities. It is unclear if ogres and ogre magi are actually the same race, or if ogre magi simply find lesser ogres easy to boss around. Typically Ogres stand between nine and ten feet tall and can weigh up to 650 lbs. Ogres are closely related to trolls, and are distantly related to the various races of giants.
http://www.wizards.com/default.asp?x=dnd/dd/20060721a
This installment looks at the ogre mage, another classic monster with the game since its earliest days. Originally inspired by Japanese mythology, a connection that has faded with time, the ogre mage is a combination of brute strength, cunning, and magical abilities. If you have a Monster Manual handy, open up to page 200 for a look at the ogre mage's entry.
http://www.dandwiki.com/wiki/SRD:Ogre_Mage
The ogre mage is a more intelligent and dangerous variety of its mundane cousin.
An ogre mage stands about 10 feet tall and weighs up to 700 pounds. Its skin varies in color from light green to light blue, and its hair is black or very dark brown. Ogre mages favor loose, comfortable clothing and lightweight armor.
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Ogre mages rely on their spell-like abilities, resorting to physical combat only when necessary. When faced with obviously superior forces, they prefer to retreat using gaseous form rather than fight a losing battle.
http://rotd.rpgclassics.com/library/races/ogre_magi.shtml
Ogre magi mailny live in oriental lands, but it is possible to meet them in other habitats too. THey are stronger and smarter than common ogres and they have even the needed requisites to become powerful sorcerors. Ogre magi are mighty foes because they are weapon masters, martial arts experts and able wizards.
Ahh crap... now I want to play D&D