Poison, etc., in a special "wine-flask" or "potion bottle".
Buckle-blades - Belt, sword-strap, or other buckle pulls off, and has a dagger on the other end.
Bootlaces - "You lace your boots with
slings?"
Inside the Boots - Slender daggers on each side of the ankle, room for a garrotte, and room inside a hollowed-out heel for a small container, which could store poison, a
Bead of Force, or other such. Heel compartments can either be accessed from inside the boot, or have an external "door".
Spiked Non-gauntlets - Springloaded spikes in tubes on the backs of the hands, worn under the gloves.
Manrikir-Gusari - A cable or chain with weights on each end. Similar to both the Spiked Chain (sans spikes, of course), and Dire Flail (also sans spikes, and without the handle). Double weapon, 1D8/1D8, 15' reach, can Disarm and Trip, be popped like a whip, as well as attack opponents within 5-10'. For disguise, the weights on the end can snap together (a pair of heavy snap-swivles, for example), and be worn under a girdle or sash. Can be used as a size L weapon, two-handed (best for disarming), or two size M, or a M and S (for two-weapon fighting) by choking up on the grip. Can also be thrown like a bola (Reflex save or be Entangled). Requires an Exotic Weapon Proficiency to use without the -4 Non-Proficiency Penalty.
Two-piece Staff - A staff that unscrews in the middle. Inside is a spear blade, and the other (sheath) end can screw onto the non-spear side.
Halbard-Spear - As above, except the Halberd's shaft contains the spear blade.
Polearm-Staff - With nearly any reach weapon, once the opponent is inside your reach, the weapon becomes useless, and must be dropped. If you are proficient with the staff, however, just use the other end as a staff, two-handed.
Ranseurs/Spetums - Any rod/staff which can contain a Spear can also contain a few more short side blades, making a Ranseur- or Spetum-like weapon.
Hairbrush - Head removes to reveal dagger blade.
Razor-Lance - A double weapon with slashing spear blades on both ends (like Darth Maul preferred). EWP required, or -4 Non-Proficiency Penalty. As with the other hidden spear-weapons, above, the Razor-Lance could also have both blades retractable...
Comb-blade - Similar to the Hairbrush-blade, above. This comb has a handle on it, which pulls loose from the comb's "teeth" to reveal a dagger blade.
Nightstick-Spear - This short, simple metal club is hollow, and unscrews. Inside is a spear-like blade as long as the Nightstick. The "sheath" screws to the rear end of the blade, forming a short spear.
Flying Blades - Any retractible blades, above, can be spring-launched to do thrown-dagger damage, instead. Requires an EWP.
Hollow "steel pipe" weapon handles - Besides containing spear blades, they can contain other things, or be loaded with spring-launched crossbow bolts. (Dwarves would love these!)
Bowklers - This Elven weapon consists of a spiked small shield attached to the grip of a bow (usually Masterwork Mighty Composite Longbows). The shield and bow/blade can be used in the same round, with no penalties. This is a racial weapon, for Elves.
Pen-knife - Not only does it write, but the opposite end removes to reveal a "letter-opener" which can also open other things... (like a mugger's neck)! Very popular with Magi and scholarly Clerics.
Spring-loaded Holy Symbols - Contain small dagger blades. Very popular with Clerics.
Shovel-spear - You figure it out...
::Shew!:: There're more, but I'm tired...