What are the stats of an Alik'r Curved Sword and where do I get them?

I think the weapon you are looking for is the Scimitar.

It cannot be bought from any vendors, however, there are some ways to obtain it. One of them is when there are two Alik'r warriors looking for a redguard woman in whiterun ( a quest named In My Time of Need). Just kill them and take their equipment.

The stats are mediocre, it is almost the same as the Elven sword.

Weapon base power is "11", which puts it at the same damage as Elven Sword, Nord Hero Sword, and Skyforge Steel Sword.

http://www.uesp.net/wiki/Skyrim:Weapons#Nord_Hero_Sword

The attack power can be augmented by blacksmithing. It is further improved by Steel Smithing.

As for where to obtain:

http://www.uesp.net/wiki/Skyrim:Specialty_Gear#Scimitar

• Curved sword carried by Kematu and Alik'r warriors.
• Can be found under an upturned canoe on the coastline west of Dawnstar. Also carried by corsairs on the Dainty Sload.
• Velehk Sain and Housecarl Rayya (HearthFire) also carry two of them.
• One is found in the Wreck of the Strident Squall next to a dead Redguard in the area reachable past the flooded section of the ship (Dragonborn)

As for how good they are, if you put effort into keeping blacksmithing high, they'll do fine. Just save a pair for end game enchanting. At the end game the weapon damage becomes almost irrelevant. I dual wield two Blades Katanas because... Katanas.