I think the Shang gou is what you are looking for.
Flails are also both Tripping and Disarming weapons.
So, both Disarm and Trip require the same prerequisite, the Combat Expertise or the Dirty Fighter feats. So it does make sense to have both.
JuliusCromwell wrote:
what would be a good build (Race & Class(es) TO make use of them
Generally, when it comes to Combat Maneuvers, the larger your size, the better. So, if you can, Half Giant or Goliath? Both have the Powerful Build Racial Trait: They are considered 1 size larger than they are. Half Giant is a Psionic Race. Goliath is a 3.5 Race. Off the top of my head, I can't think of any Pathfinder Races that are size large or have Powerful Build.
Druids can increase their sizes 2 places with Wildshape. Goliath Druids can turn into Monstrous Humaoids (Giants), so get to use their regular gear.
The Living Monolith Prestige Class lets you use Enlarge Person on yourself as a Spell-like Ability as a Swift Action.
The Monstrous Physique Spells let you Polymorph into big Monstrous Humanoids.
So, choice of weapons:
The advantage of using a Tripping Weapon is that sometimes you have a catastrophically bad roll, and you are Tripped by your own trip attempt. But if you are using a Tripping Weapon, you can elect to drop your weapon rather than get Tripped yourself. But if your Trip weapon is something big like a Halberd or a Horsechopper, you are likely to miss that weapon when it's gone. If you are Tripping with a Sickle and you lose that, you shrug your shoulders and pull another one off your belt. In 3.5, there was a distinct advantage to using a 2 handed Disarming Weapon. in Pathfinder, there isn't. I think Shang gou is a solid choice for you.
Consider using a Light Flail in 1 hand and a Shang gou in the other. A Light Flail is not a Light Weapon, but rather a One Handed Weapon. It does 1d8 Damage instead of 1d4.
Since Shang gou don't do much Damage, consider being a Warpirest. Warpriests do not do their regular weapon Damage, but rather their Sacred Weapon Damage, which goes up with levels sort of like Monk Unarmed Strike Damage.
The really cool thing about fighting someone whom you just Disarmed or Tripped is Attacks of Opportunity. If they attack you without a weapon, you get an Attack of Opportunity. If they try to get up after you Trip them, you get an Attack of Opportunity. If you have Greater Trip, you get an Attack of Opportunity as they go down. If they continue fighting while Prone, they get a -4 to attack you, and you get a +4 to attack them (,or maybe they get a -4AC, I forget, and sometimes that makes a difference). So you want lots of Dexterity and the Combat Reflexes Feat.
Monks are full BAB when it comes to Combat Maneuvers, and there is a Style Feat Tree, Ascetic Style, that will let you inflict your Unarmed Strike Damage instead of Shag gou Damage and let you do other cool Monk stuff as well. Monks get Combat Reflexes as a Bonus Feat.
There is a Feat called Vicious Stomp which gives you an Unarmed Attack of Opportunity on anyone that Fall Prone in one of your Threatened Squares, and Falling Prone is considered not quite the same thing as being Tripped. So if you had both VS and Greater Trip, you would get 2 Attacks of Opportunity: 1 for Tripping them and another for their falling Prone.
I guess you might be an Unchained Rogue. Take Weapon Finesse for your Shang Gou and you also get Dex-to-Damage for them. Take Agile Maneuvers, and you get to use your Dex Mod instead of Strength for Tripping and Disarming. Instead of increasing your Base Damage like you do with Warpriest or Monk, you get Sneak Attack Damage, so also start taking Dirty Trick Feats to Blind your opponents and get your SAD that way. Improved Dirty Tricks also builds off of Combat Expertise.
There is another Feat, Fury's Fall, which lets you add both your Strength and Dex Mods to your Trip Roll.
A problem with Tripping, is that there is a size limit. You can't Trip anyone who is 2 or more Sizes bigger than you. I hate this rule. It is a stupid rule for stupid studipheads. But it's a rule. There it is.
There is a Wondrous Item, Belt of the Impossible Maneuver, which lets you Trip big people.
There is a Teamwork Feat, Harder they Fall, which also lets you get around the rule.
Punishing Kick lets make any size creature fall Prone, which is not the same thing as Tripping. It's like Stunning Fist, but instead of Stunning, they fall Prone.
