Well rested effect will already increase skill gain rate.

Memory potions could be interesting. The main goal of skill loss on death is to make players actually play as well as they can and not leeroy around. Using costly enough materials (and I do mean actually costly, in a way no one of us can even dream of yet) found primarily in the final two biomes to get a drinkable buff to further increase skill gain, reduction of penalties, or recovery of points wouldn't be outlandish.