Weapon Mastery by nation
I also assume that there would be some correspondence between the type of weapon and the country (or city) where you would have to go to find the Grand Master of your weapon of choice. For instance, Alfheim Town could be a good place to start looking for a Grand Master of Longbow Archery.
by Giampaolo Agosta
Sling: Five Shires
Shortbow: Five Shires, Alfheim, Thyatis, Ethengar, Atruaghin
Longbow: Alfheim
Light Crossbow: Thyatis, Rockhome, Glantri, Darokin
Heavy Crossbow: Rockhome, Thyatis
Battleaxe: Rockhome, Northern Reaches
Longsword: Thyatis, Northern Reaches, Heldannic Territories, Alfheim
Rapier: Darokin, Glantri
Dagger/Main Gauche: Thyatis, Darokin, Minrothad
Saber/Scimitar: Ylaruam, Ethengar, Thyatis
Lance: Kerendas, Ylaruam, Heldannic Territories
Mace: Ochalea
Hand Axe: Rockhome, Northern Reaches, Atruaghin
Short Sword: Five Shires, Thyatis
Javelin: Thyatis
Throwing Hammer: Rockhome
Two-handed sword: Darokin, Thyatis, Heldannic Territories
Bastard sword: Northern Reaches, Klantyre
Other weapons seem less likely to have Grand Masters (and even a few of the ones mentioned here might only have Masters).
by Greg Weatherup
Adding to Agathokles list:
Heldann should probably also have Maces, Crossbows, & war hammers
Wendar could have Hand Axe and bows
Add Belcadiz for Rapier
Bola grandmasters would probably only be found amongst the Gaucho's of the Savage coast
Cestus: Thyatis
Club- just about anywhere I'd imagine
Crossbows: Heldann, maybe Minrothad?
Dagger & Staff's: Alphatia (as someone else mentioned) & also Glantri maybe Yavdlom
Spears & Swords are pretty much everywhere, but I'm not sure about where else Javelin's could be found
Blackjack's & Whips I'm not sure on.
Personnally I've never used the Shield Weapons, so I won't comment on them
I notice Ierendi hasn't shown up on any list yet..... Isn't there anything that might be found there?
What about in the Broken Lands for humanoid characters-
Isn't the symbol of the Bugbears of Ogremoor a trident? Might there be a trident GM there?
Similarily Yellow orkia and Red Orcland might have shortbow GM's
Thar's legion has some trainers right?
Also Hule probably has various GM's willing to train humanoids
And this doesn't include Davania nor Skothar lands...
by Matthew Fleet
Blackjacks, blowguns, bolas, whips and nets are mainly thief style weapons, so I would suggest Landfall (the City of Thieves) in Norwold as a place where Grand Masters of these weapons could be found. I also agree with Gecko that the Savage Baronies would also be an excellent place to train in the bola.
by Giampaolo Agosta
Blackjack: that's much more of a Thief weapon than any other, the Landfall suggestion works perfectly for this weapon.
Blowgun: Ulimwengu?
Bolas: definitely Guadalante; also Goblinoids of the Pampa Rica.
Net: more than a Thief weapon this is a gladiator's weapon. Thyatis seems the best option.
Shield Weapons: definitely rare, although as gladiator's weapons, Thyatis is always an option.
Ierendi: anything, but fairly randomic -- many adventurers in Ierendi come from other nations, and have developed personal or hybrid fighting styles. OTOH, the nation itself is small, and there are few very powerful adventurers (the levels of the King and Queen, who are supposedly the best adventurers, should be indicative of the top ranking Kia'i).
Humanoids: the rules impose heavy limits on humanoid weapon mastery, and in particular only humans and demi-humans can be Grand Masters (see the RC). Personally, I ignore this rule.
If so, then the following masteries could be easily found:
Ogres: club (and variants)
Bugbears: longbow, battleaxe, morningstar/mace
Orcs (Orcus Rex): (bastard) sword
Orcs (Red): hand axe, short bow, spear
Hobgoblins/Yellow Orcs: scimitar, spear, short bow
Goblin: spear, lance, shortsword
Gnoll: halberd, scimitar, battleaxe
Kobold: spear, shortbow, net