I did not manage to get any more of Jarvis' soul splinters lately, so upgrading him is pretty much at a halt at the moment. But then I realized I could upgrade the skill that would allow lesser gold for healing.
These are the Mysterious Caves with chance of obtaining the skill scrolls, all the odd numbered up to level 11. I tried my luck yesterday on level 1 cave for 6 times but couldnot get any. Well ya, if I have nothing to do later, I would try again.