The array of armaments available to archers, armigers, assassins, and the like has grown considerably since Paizo first published the fighter and the categories of weapons used in the class's weapon training ability. Ultimate Combat, Ultimate Equipment, and Melee Tactics Toolbox all did admirable jobs of cataloging to which category each of the new weapons belonged, yet some implements of destruction have never received this treatment—especially those that are iconic weapons in on Golarion.
For the majority of these—by my count—290 weapons, there's little doubt as to where a given weapon falls (at least I hope we agree that a barbed spear does, in fact, fall into the "spears" category). For some it's a little less clear. In the Pathfinder Society Roleplaying Guild, players have done an admirable job of making educated guesses when wielding battle poi or a ripsaw glaive regarding which category to use. However, it's nice to have confirmation about these things to minimize any table variation that might otherwise hamper the PC. In fact, players have requested this clarification time and time and time again.
For those participating in the organized play program, this blog is going to appear as one of the legal sources on the Additional Resources page. If you're running a home game, you're certainly welcome to use it or disregard it as befits your campaign and play style. Especially in light of the upcoming Player Companion: Weapon Master's Handbook, I hope that perusing the list inspires you to use some obscure weapons you hadn't considered and build even more exciting characters.
Any weapons that appear in Ultimate Combat, Ultimate Equipment, or Melee Tactics Toolbox have not changed categories, though following discussions with the Pathfinder design team, a few more weapons were added to the Double Weapons and Thrown group. Any other weapons originate from Campaign Setting: The Inner Sea World Guide, Campaign Setting: Distant Shores, Player Companion: Adventurer's Armory, Player Companion: Cheliax, Empire of Devils, Player Companion: Dwarves of Golarion, Player Companion: Gnomes of Golarion, Player Companion: Halflings of Golarion, Player Companion: Humans of Golarion, Player Companion: Ranged Tactics Toolbox, Pathfinder RPG Advanced Player's Guide, Pathfinder RPG Advanced Race Guide, and Pathfinder RPG Monster Codex (and possibly another book or two I didn't note while listing references).
Thanks also to Andrew Christian, Dave Higaki, and Robert Thomson for their assistance in reviewing these lists and tracking down a few weapons I missed.
Axes: Bardiche, battleaxe, boarding axe, collapsible kumade, dwarven double waraxe, dwarven longaxe, dwarven maulaxe, dwarven waraxe, gandasa, greataxe, handaxe, heavy pick, hooked axe, hurlbat, knuckle axe, kumade, light pick, mattock, orc double axe, pata, throwing axe, and tongi
Blades, Heavy: Aldori dueling sword, ankus, bastard sword, chakram, cutlass, double chicken saber, double walking stick katana, elven curve blade, estoc, falcata, falchion, flambard, great terbutje, greatsword, katana, khopesh, longsword, nine-ring broadsword, nodachi, rhoka sword, sawtooth sabre, scimitar, scythe, seven-branched sword, sharpened combat scabbard, shotel, switchscythe, temple sword, terbutje, and two-bladed sword
Blades, Light: Bayonet, blade boot, brass knife, butterfly sword, chakram, dagger, deer horn knife, dogslicer, gladius, hunga munga, kama, kerambit, kukri, kunai, machete, manople, pata, quadrens, rapier, ratfolk tailblade, sea-knife, short sword, sica, sickle, starknife, switchblade knife, sword cane, swordbreaker dagger, tailblade, wakizashi, and war razor
Bows: Composite longbow, composite shortbow, longbow, shortbow, and thorn bow
Close: Armor spikes, barbazu beard, bayonet, blade boot, brass knuckles, cestus, dan bong, dwarven boulder helm, emei piercer, fighting fan, garrote, gauntlet, heavy shield, hook hand, iron brush, klar, light shield, madu, mere club, punching dagger, rope gauntlet, sap, scizore, shield spikes, spiked gauntlet, tekko-kagi, tonfa, unarmed strike, wooden stake, and wushu dart
Crossbows: Crank crossbow (heavy), crank crossbow (light), double crossbow, gastraphetes, hand crossbow, heavy crossbow, launching crossbow, light crossbow, repeating hand crossbow, repeating hand crossbow, repeating heavy crossbow, repeating light crossbow, slaver's crossbow (heavy), slaver's crossbow (light), stonebow, tube arrow shooter, underwater light crossbow, and underwater heavy crossbow
Double Weapons: Battle ladder, bo staff, boarding gaff, chain spear, dire flail, double walking stick katana, double-chained kama, dwarven double waraxe, dwarven urgrosh, gnome hooked hammer, halfling double sling, kusarigama, monk's spade, orc double axe, quarterstaff, taiaha, two-bladed sword, and weighted spear
Firearms: All one-handed, two-handed, and siege firearms
Flails: Battle poi, bladed scarf, cat-o'-nine-tails, chain spear, dire flail, double chained kama, dwarven dorn-dergar, flail (light flail), flailpole, flickmace, flindbar, flying blade, gnome pincher, halfling rope-shot, heavy flail, kusarigama, kyoketsu shoge, meteor hammer, morningstar, nine-section whip, nunchaku, sansetsukon, scorpion whip, spiked chain, urumi, and whip
Hammers: Aklys, battle aspergillum, club, combat scabbard, dwarven longhammer, dwarven maulaxe, earth breaker, greatclub, hanbo, heavy mace, knobkerrie, light hammer, light mace, mere club, piston maul, planson, taiaha, tetsubo, wahaika, and warhammer
Kobold Tail Attachment: Long lash, pounder, razored tail attachment, spiked tail attachment, and sweeper
Monk: Bo staff, brass knuckles, butterfly sword, cestus, dan bong, deer horn knife, double chained kama, double chicken saber, emei piercer, fighting fan, hanbo, jutte, kama, kusarigama, kyoketsu shoge, lungchuan tamo, monk's spade, nine-ring broadsword, nine-section whip, nunchaku, quarterstaff, rope dart, sai, sansetsukon, seven-branched sword, shang gou, shuriken, siangham, tiger fork, tonfa, tri-point double-edged sword, unarmed strike, urumi, and wushu dart
Natural: Unarmed strike and all natural weapons, such as bite, claw, gore, tail, and wing
Polearms: Bardiche, bec de corbin, bill, boarding gaff, crook, fauchard, flailpole, glaive, glaive-guisarme, guisarme, halberd, hooked lance, horsechopper, lucerne hammer, mancatcher, monk's spade, ogre hook, naginata, nodachi, ranseur, ripsaw glaive, and tiger fork
Siege Weapons: Ballista, bombard, catapult, corvus, firedrake, firewyrm, gallery, ram, siege tower, springal, trebuchet, and all other siege engines (see Ultimate Combat for more details)
Spears: Amentum, barbed spear, boar spear, boarding pike, chain spear, doru, elven branched spear, flask pike, javelin, harpoon, injection spear, lance, longspear, orc skull ram, pilum, planson, sarissa, shortspear, sibat, spear, spear-sling, syringe spear, tiger fork, totem spear, trident, and weighted spear
Thrown: Aklys, amentum, atlatl, blowgun, bolas, boomerang, chakram, club, crystal chakram, dagger, dart, deer horn knife, dire bolas, doru, flask thrower, grappling hook, Halfling double sling, halfling sling staff, harpoon, hunga munga, hurlbat, javelin, jolting dart, lasso, kestros, knobkerrie, kunai, light hammer, net, phaleros, poisoned sand tube, rope dart, shortspear, shrillshaft javelin, shuriken, sibat, sling, sling glove, snag net, spear, starknife, stingchuck, syringe spear, throwing axe, throwing arrow cord, throwing shield, trident, wahaika, and wushu dart