I chose not to kill parthurnax (sp)...

Does this mean I am no longer on good terms with the blades? Can I still do the blades recruitment?

I just felt like Parthurnax redeemed himself by helping me so I chose not kill him like they asked me to.

Nope, all done. If you don't kill Parthy the mighty Blades (all 2 of them) will sit in the stone cold Cloud Ruler Temple all alone for eternity. What exactly it is Delphine and Esbern are doing in there for eternity while you are gone is up to your own imagination.

Make sure to loot the Blades Armour set from the chest if you want that.

Nope. You're not missing out on much either.