You might be interested in threads from the FAQ section on "How historically accurate is Game of Thrones / A Song of Ice and Fire?":

##Specific Comparisons

-Warfare and Tools of War

-o- Could castles have been built over geothermal spots? Like some castles in the world of ASOIAF are? (95 comments | over 3 months old)

• Commenters here discuss the general types of medieval castles, castle uses, castle garrisons, and also a geologist chimes in to talk about issues that geothermal spots pose for such fortresses.

-o- "'Leather armor' is a common fantasy trope. Did it really exist in premodern Europe?" (65 comments | over 9 months old)

• This thread goes into the remaining evidence of and possible uses for boiled leather as armor with a variety of book citations spread throughout the thread.

-o- "In films / tv like Game of Thrones they show medieval swords being able to slice a person in half etc. Is this realistic?" (121 comments | over 1 year old)

• Commenters here bring up various examples of executions and sword blows and the efforts involved in making sure they were lethal in various contexts from Medieval Europe and pre-Modern Japan to Colonial Mesoamerica.

-o- "Did kings and princes ever really fight in personal combat in the midst of battles?" (43 comments | over 2 years old)

• A commenter talks about how royalty participated in battle by commanding their knightly cavalry in 12^th and 13^th century France.

-o- "Were medieval sieges in any way similar to the Siege of King's Landing/Blackwater in Game of Thrones?" (12 comments | over 2 years old)

• Users here summarize how most Medieval sieges proceeded.

-o- "How common was it in Medieval times for people to name their swords?" (20 comments | over 8 months old)

• The original poster talks about a Game of Thrones example in their post body and commenters go on to describe named swords in medieval literature while a flaired user gives a very short and general summary of the markings and blessings that Medieval European warriors bestowed upon their blades.

-o- "Was there anything like the "Wildfire" from Game of Thrones in the real medieval world? [Season 2/ACOK Spoilers Inside]" (17 comments | over 9 months old)

• A flaired user compares the qualities of Wildfire with the Byzantine Empire's Greek Fire.

-Knights

-o- "Is the notion/ideal of honor that is portrayed in movies and TV of Middle Ages knights/others a modern construct or a unique/defining aspect of the times?" (11 comments | over 10 months old)

• A flaired commenter in this thread traces the image of knighthood and honor exhibited in the books and show to a specific strand of 20^th century historiography of the subject and later in the comments shows what other historiography has to say on the concept of chivalric honor.

-o- "In shows like Game of Thrones, characters wear their armor almost everywhere. How accurate is this portrayal?" (57 comments | over 9 months old)

• Flaired commenters here discuss the mobility and endurance of knights with videos of reenactments as well as academic papers and books present for further viewing and reading.

-o- "During the medieval period, did knights and soldiers wear the colours of their lord in battle, their own heraldry and colours, or a mix?" (23 comments | over 9 months old)

• Even though the topmost comment is an answer concerning Feudal Japan, there is a remaining top level comment detailing the purpose of Medieval European heraldry in battle.

-o- "Were there any feared knights from medieval history like the Mountain from Game of Thrones?" (25 comments | over 8 months old)

• Commenters in this thread bring up English, Irish, French, Polish, and Crusader examples with copious sourcing present throughout.

-o- "Were knights/Medieval soldiers as brutal and remorseless as depicted in 'Game of Thrones'?" (14 comments | over 1 year old)

• Commenters here narrow down the comparison to English knights during the War of the Roses and Westerosi knights before delving into the details of the differences between the historic and fantastical variations.

-Followup Questions

These users are flaired on the topic and/or have answered questions on it in the past, and would likely be able to answer specific questions not covered in the above threads:

-o- /u/Rittermeister

-o- /u/TheGreenReaper7

-o- /u/idjet