Disarm and Sunder are indeed not great. They are OK for Bandit and Pitax chapters, and Sunder helps with Val's quest duel, but overall skippable.
Trip is good, prone is a great status effect. Greater Bull Rush is good too, if you have 3 or 4 melee guys because it provokes AoOs. The Charisma-based debuff ones (Cornugon Smash, Dreadful Carnage) are also quite good and Val should take them if you use her.
I don't know... My problem is - why should my full BAB optimized fighter with strength through the roof waste a round applying debuff effects when he could be smashing losers in the face for ridiculous damage. I got a whole range of free-loading sluts to debuff and cc, there's no point in having my guy wave his sword through empty air dazzling enemies with unashamed gayness.
Trip/disarm/sunder, dazzling faggotry should be on hit effects not separate actions imo.
In the end it comes down to - do I really need an ability that helps me kill losers in more creative ways when said losers could be defeated anyway ? I would much rather prefer an ability that's a game changer against enemies that would otherwise pose a real threat.
And Valerie sucks a thousand cocks. Gimp class, gimp character design, fuck that bitch and the drunken vata who made her.