Deep Wounds will help you quite a bit with threat. I see little point in grabbing Impale but neglecting to grab Deep Wounds.
You also should reglyph. I would run with Devastate and Shield Wall glyphs at all times (make sure to grab the Improved Disciplines talent, to make Shield Wall a 40% cooldown every 2 minutes - very handy), and then swap out the third glyph depending on the fight. Last Stand, Taunt, Cleaving, Blocking, Vigilance - there are a lot of viable options, get a scribe to make you several stacks of glyphs and just play with them for different fights. (glyphs are very cheap if you have a scribe friend)
http://www.wowhead.com/talent#LAM00f...rx0didIzsGo:cT is the new cookie-cutter Deep Wounds spec. (One popular tweak is to pick up 5/5 Shield Spec at the cost of 0/3 Focused Rage, this is a personal choice)