One problem I've had with increasing strength/craft through trophy exchange is that once you get to a certain level, every battle with a 7+ enemy (very common when playing with The Dragon expansion) you automatically get an extra point with battles getting exponentially easier.
One way I thought to get around this would be to only allow trophy exchange for 2x your current strength/craft (excl. items/followers etc.). This should even out the levelling a little and make it easier for characters with low starting levels a chance to get on the levelling up ladder earlier.
Thoughts?