I always have a huge surplus of progression points compared to the amount of money I can spend on training. So what I would like is a way to spend progression points to improve skills, either without money or with a lot less money.
What I think sounds best is that, for every other level and still limited by the maximum level of the last trainer you visited for a particular skill, you can spend progression points without a trainer. This might take 5-10 times the progression points, but no money. It would not work for abilities, only skills.
For example, lets say my swords skill is 33 and I pay a trainer for some theoretical knowledge. Then I go out and practice until I am level 34. Currently I must now return to a trainer to get more theoretical knowledge. I propose that, at this point, I can give myself the theoretical knowledge for level 35 by spending 5 times the normal progression points, but no money. Or maybe be partially self taught and partially trained.
Instead of the every other level thing, maybe you acquire the last step of theoretical knowledge from a trainer. So if I have just turned level 34 I can fill the yellow bar with green all the way to the last step without a trainer, but that last step to get all theoretical knowledge needed requires a trainer. That would take a lot less change to the database and code. That way, if you have a lot of progression points, you can get a level for only 30 tria. Or maybe instead of just the last point, the last quarter or third of points must be purchased from a trainer. By having a cap at every level, there is no extra data to store, just a test of wether you are below the limit and thus can spend points.
A third option would be the ability to buy practical knowledge with progression points. I like the differentiation between theoretical and practical experience and so do not like this idea as much, but in a sense progression points directly represent practical knowledge.
Either way, I envision clicking the buy skill button when no npc is selected would use this alternate method. When an npc is selected, only the skills they train could be improved and only at normal cost. I also figured that this would not work on abilities, only skills.
Right now I feel like all those progression points are wasted and serve no purpose. The game could basically do without them and just charge money, because money is so much harder to get. Letting players spend just progression points would balance that out, and also encourage players to diversify their skills. Right now I can only afford to focus on a few skills. Even if the price is exorbitant, like ten times the normal progression point cost to gain the theoretical knowledge for a level, at least I could spend the points on something.
Or maybe I am missing something and there is a much easier way to make money. Or maybe you should only gain a progression point every 1000 experience points instead of every 200. Or training should just cost a little less. But if you can spend the progression points, at least a little, you will come to a natural balance between money and experience, instead of adjusting the artificial balance currently in place.
Also, holding a modifier key like shift should buy all the training you can get for an attribute or skill in one go. Sitting there clicking the buy skill button a few hundred times might reproduce the ennui of theoretical training, but I would rather do without.
Thanks for a great game.