I am a lvl52 Battle Summoner now and I have to say that at this point combat support is not cutting it. Power support is simply much better than combat support. Both ingame and by calculations, combat support is simply a very weak buff.
I have power support lvl10+2 and combat support lvl3+2
The first problem with combat support is that the games math engine rounds down buffs. e.g. the skell has a +4% (@ lvl 5) atk speed self buff. With an axe my skell has 70 atk spd. +4% should give 72.8 atk spd. If anything the atk spd should be 73 but the in game reading is 72.
When I add lvl 3 combat support(+2) which is a 9.8 % increase the result should be (using the 72.

~79.9 atk spd. In game the result is 79.
On a skell using the feast of wind lvl5 (+4% atk spd) and a lvl1 unenchanted r3 2h axe (with 2 +5 str stones = +20 patk) the dps is 224.64. With combat support lvl3+2 on the 9.8% increase results in a dps of 246.48 using the same axe. Cool right? Wrong! using the same axe and lvl10+2 power support instead of the lvl3+2 combat support the skell now has a dps of 267.84 (due to the +60patk).
In other words +60patk increases the dps more than +9.8%atk spd.
Add in the 360 additional hp from power support and combat support has no uses at present for me.
Also where the dirk issue is concerned:
1) The dps of a single dirk just sucks period. Using a similar dirk (r3 lvl1 unenchanted with 1 +5 str stone = +10 patk) the skell now has a dps of 154.7 with feast of wind lvl5 and combat support lvl3+2 and 207.1 with feast of wind lvl5 and power support lvl10+2.
In other words dont use a dirk on your pet as a sorc.
However please note that for the sorc itself the dirk will be the best choice of weapon once you have your weapon mastery to the full lvl20 in addition to the double buff as well as the occasional block that the shield gives. Until then the best choice of weapon for a young sorc/B.Sum is actually a 2 handed axe. (Also note that charge stab and dark strike produce significantly more damage with a 2handed axe).
2) You lose out on 2 stone slots when using a dirk.
Back to the original topic:
Combat support on its own is very weak.