Ninjatō

Ninja-To is a sword which is used for slashing attacks which inflict 1d8 points of damage and has a reach of 1 ft. It requires one hand to wield the weapon and at least 6 strength. The weapon has a weight 5 and a speed factor of 4. This weapon can't be used by druids and clerics due to their ethos and mages and sorcerers aren't skilled enough to wield this weapon. This item appears in Baldur's Gate II: Shadows of Amn and Baldur's Gate: Enhanced Edition. It's sold by most weapon stores in these games.

In-game description
"Ninja-To The sword of the ninja, the ninja-to, is of lower quality than other Kara-Tur blades such as the katana.  The ninja-to is short with a straight blade, making it ideal for the subterfuge of the ninja.  The ninja-to is also more suited to fighting in closed places, sometimes giving the ninja an advantage over the longer blades that the samurai used."