ok now that i've praised him, i must point out two things martin does that drive me up the frickin' wall. but before i start, i must note - though i've read a lot about heraldry, i am not remotely a medievalist and at least two of you are, so please correct me if i say something totally off.
the two things i'm referring to are simple: heraldry and armor. martin is constantly giving these lush, loving descriptions of gleaming mounted knights in enameled or inlaid armor, usually (always?) with massive complicated crests on the helmets. ok. dude. have any of you even heard of enameled armor? lacquer or enamel on armor would crack and break off as soon as anything hit it. it would be impossible to lacquer any bits - like, say, gauntlets - that involved a lot of lobstering of the steel, or any joints at all, really. now, i know that there was plenty of inlaid armor, but he keeps describing knights actually going into battle and tournaments wearing elaborately gold and silver-inlaid armor with like, gold rondels and shit. how on earth would any but the most obscenely rich of knights have the kind of money needed to wear gold-inlaid armor into a situation where the stuff is bound to get fucked up? the richly-inlaid stuff i've seen in museums has been stuff like henry VIII's armor on display in the Tower, and somehow i doubt henry was in the press laying about with his mace. can you imagine /anyone/ - ever! - going into battle with a breastplate inlaid with /rubies/?
i think what bothers me most about the armor thing is that martin could easily have gotten around the enamel/inlay issue - if he's so fond of coloured armor - by making it clear that in his world smiths have some way of colouring steel -- in fact, he actually /does/ do this in places; the colour is somehow in the steel. ok, fine, it's an alternate universe where valyrian steel is unrealistically sharp due to mysterious processes, so i can accept coloured steel -- /if/ it's produced with clearly-stated mysterious processes.
martin also has that nasty habit regarding crests - i just read a description of a party of knights riding out to battle with all these fancy crests (and of course the baratheons wear their huge golden stag horns). i was taught in history class that no one with any sense worse crests even to tournaments, because weapons get /caught/ in people's useless damn crests. who on earth is going to waste energy holding up /golden horns/ while trying to kill people in a melée?
but what bugs me even more is heraldry. oh my god! ok, there's one heraldic colour combo - it's ser dontos' colours, i think - that is described as crimson and scarlet. wtf? i can't even visualize that! that's an extreme case, but martin constantly breaks the rules of heraldry. heraldry was designed with a very simple goal in mind: making sure everyone on the battlefield could recognize people from far away. you cannot tell the difference between sky-blue and cyan from fifty yards away, for god's sake, or between butter-yellow and gold, etc etc, and martin insists on distinguishing heraldic colours this specifically. he also violates the rules on what colour combinations are acceptable - for instance, as i understand it, two dark colours, say blue and red, must be seperated by a light colour like white or yellow, again because it can be hard to distinguish those things from a distance. most modern flags still follow these rules, which is why the white in the french and italian flags is in the middle, not on one of the sides (but the italian's not a good example, since iirc orange is not actually a traditional heraldic colour - which you wouldn't know from martin).
this bugs me especially because the man seems to do such a good job showing other aspects of medieval life (again, not that i know all that much) ... and he collects model knights, for god's sake. he should know better.