AEG's Swashbuckling Adventures stats its Sword Cane as an exotic weapon with the same properties as a rapier for the blade portion. As an additional property of the weapon, when weilded as a cane instead of the bladed insert, it acts as a club that deals 1d4 damage.
They allow weapon finesse (sword cane) to apply to either use of the weapon. Their version also carries a -1 penalty to AC when fighting enemies wielding fencing blades (representing fighting with a weapon that lacks a guard).
Hope that helps with your development, and I highly recommend taking a look at AEG's book if looking for idea on adding a little flare to standard combat.
-Rill