It seems to me there's a number of missing special abilities that would enhance The Witcher 2. Feel free to add your own!

Magic Branch

Faster than the Die
Grants Geralt the ability to catch dice flung off the poker board and re-roll them
Level 1: Geralt can catch and re-roll one die
Level 2: Geralt can catch and re-roll two dice.

Axil's Reversion
Geralt enhanced influence with women results in him getting bedded as frequently as he did in the first Witcher.

Axil's Subversion
Affected creatures, instead of fighting for the Witcher, agree to carry his stuff. Doubles the number of items he could normally tote.

Axil's Perversion
Acts just like Axil's Reversion, except his charisma affects men, not women.

Alchemy

Drunken Master
Geralt gains 5% Damage Reduction in brawls, when inebriated (also counts when getting slapped by indignant barmaids).

Not Only Elves Love the Forest
Geralt's potion bottles are now reusable, so he doesn't litter everywhere.

Swordmanship

Somersault
Geralt's dodge actually results in leaps over foes, instead of ending up at their feet and just begging for a swift beheading.

Fight Another Day
Geralt can actually retreat from battles and run like crazy, ignoring invisible walls. If a kayran is in pursuit, it also doubles his speed.

Detect Weakness
Geralt can locate the precise location of any male opponents "special vital area" (gnads), for the delivery of a swift kick and increased stunning chances.
Level 1- Works against humanoid foes, only. Stun +50%
Level 2- Works against monsters as well. Stun +75%.

It should be noted this ability doesn't work against the females of any species (exception: dwarves).