Lajatang

The lajatang is a staff with a crescent-shaped blade at each end. A lajatang is a double weapon. You can fight with it as if fighting with two weapons, but if you do, you incur all the normal attack penalties associated with fighting with two weapons: a one-handed weapon and a light weapon.
A monk who is proficient with the lajatang can treat it as a special monk weapon, as described in the monk class description. Each end counts as a separate weapon for the purpose of the flurry of blows ability, similar to how the quarterstaff works.

Cost: 90 gp
Damage: 1d6/1d6(S) 1d8/1d8(M) 2d6/2d6(L)
Critical: ×2
Weight: 7 lb.
Type: Slashing

Source: Complete Warrior