Kerambits require a bit of retraining, both physically and mentally, in their use. The biggest thing for most folks seems to be thinking of it as 'a knife', when it really isn't, at least in the functional sense.
A Kerambit, particularly in reverse (blade on pinky side, edge on knuckle side) grip doesn't really work anything like a 'knife' as we usually use them, and so treating it as something completely new and unique seems the key to learning to use one correctly, IMHO.
Larry