Okay, if you wan't to be like EVERY other 29 Rogue in this bracket, go Daggers, 16/0/4 or 15/0/5.
The burst from Daggers is great, you get 400-500 Backstab crits ocassionally, which is pretty nice. I find Daggers pretty annoying when fighting Hunters, Swords is as good as Daggers, it isn't burst, but it's substained dps. I get around 200 SS's and 150-300 melee swings, which is awesome.
But if you wan't to be different from EVERY other 29 Rogue in this bracket, try Swords, 0/20/0, 5/12/3, 0/17/3, or even 7/0/13(Sub).
My favorite is 7/0/13, a.k.a Bleed Spec, it's great when fighting Rogues, Warriors, etc, any class thats kitable really. In the battlegrounds it stills does decent damage and it's fun.
Don't let anyone tell you combat sucks, just because 95% of the Rogues in the 29s bracket are Daggers doesn't mean swords suck, don't be one of those guys, go ahead and try Swords.
As my experience of being Swords for a year, I find it easier to kill, puts out more damage, etc.
For the Axe with Mongoose question, I would get it, but it's only 1ppm, which isn't all that great.
It's pretty much the choice of burst or substained dps, also If you want me to post the specs I will if you want me to.
Armory my Rogue, Zeiren. Also another good Combat Rogue is Kuntuhkinte, except I would put full 20 in Combat.
If you have any other questions just ask me.
Edit: ^