Thanks to generous help from other users I was able to pull off a very successful build consisting of Swashbuckler 5/Barbarian X.
The dex boosting rage (or rather Serenity from the 3d party Serene Barbarian) helps me land most hits and rack up an impressive amount of damage each round combined with Fencing grace and the Swashbuckler Opportune Parry & Riposte.
Obviously, I'd like to delve further into barbarian levels to prolong the duration of rage (6 rounds is barely cutting it right now). The thing is that my second level of barbarian won't tick in until level 7. I dipped once at level 2 to get the rage feature, but I strongly wish to prioritize two more levels of Swashbuckler (currently Swash 3/Barb 1) in order to nab the bonus feats at lvl 5 and Weapon specialization (more ab/dmg and improved critial early and free) as quickly as I can to be more functional.
To get to the point; What rage powers are viable at level 7? The levels will progress slower, so any scaling bonus seems hardly worth it. My first rage power will come in at 7th, the second and 9th, 11th and so forth..
+2 dmg/-2 ac from reckless abandon at level 9, seems fairly underwhelming.
Option A) Possible Rage powers:
I've been thinking of going with Fight response or guarded life at 7 and then delve into renewed vigor at 9 and go from there. Alternately pick superstition at 9th and ghost rager at 11th.
I've also thought about the moment of clarity line.
Impelling disarm has also been noted, hadn't it been for my rather sub par CMB from being a finesse fighter. I could go for quick reflexes which would allow me to take agile maneuvers at lvl 5 in stead of combat reflexes, but I feel that I'd rather have combat reflexes' not-rage dependent use in the levels to come as it's near mandatory for the swashbucklers deeds to be effective.
These were previously suggested to me and are quite good picks which would definitely give the build an extra edge, though still, I wonder if their use will be too situational, too feeble or too feat requiring this late in the game.
Option B) Delve into a barb archetype that Doesn't have rage powers. I'm not sure if such an archetype exist though.
Option C) Take an extra level of Barbarian and be satisfied with the +2 rage rounds and uncanny dodge, then move on to a prestige class. Here I am also completely blank as to what would suffice.
I realize I might be asking a lot, and that I've probably painted myself into a corner with the persistent multiclassing, though it doesn't hurt to check ones options.
In short; What are good late entry (7th lvl ->) rage powers, or should I branch into new territory?
Lesser Celestial Totem is good for in combat healing.
As long as you aren't using Unchained barbarian, Lesser Cult Totem is good for turning flanking bonuses into damage bonuses.
Roused Anger is good if you ever get fatigued in combat and still need to rage.
If your 6 rounds of rage seem a bit low, you could consider taking the feat 'additional traits'. This gives you 2 traits instead of a feat.
The feat Berserker of the Society would increase your rounds of rage by 3. You could pick something nice for your second trait.
...Or the feat Extra Rage for 6 extra rounds of rage.