I don't even know if I can really call it refactoring, since I am really just changing the way skills advance and the currency used for said advancement. However, it is quite a drastic change on the backend.
Previously I had thought that I would make the players seek out trainers and spend their gold on ranking up their skills, which would be found randomly through questing/as loot etc. This seemed like a good idea until it came time to actually advance the skill. What got modified? If it's a damage skill, it seems silly to change the base damage dice every single level. Not scalable. Then, I briefly entertained not making every rank do something in terms of skill effectiveness. That seemed like a cheat and a waste when I thought about it from the player perspective. All in all the system based around gold spending and trainer finding just seemed far to cumbersome, to me as a developer and a player.
So I implemented something that harkens back to my days of playing the fabulous MMORPG Asheron's Call. In that particular game, you spent your accrued Experience Points on your attributes and skills. This is obviously a VERY open system, and is designed to be as such. However, Avaloria aims to be very open in terms of character development. You CAN wear plate armor and cast spells. You may fail a slight bit more than others, or possibly have some spell backlash due to the metal armor, but that chance will be small if you specialize into a class designed for battle magic use. Classes will never be mandatory, and most skills will be available to all classes/non-classed characters.
To that end, skills now have a backend component that is merely a floating number which starts at .01. Each point added to the skill (using Experience Currency) will relate on the backend to a 1% increase to the skill's rank modifier. This rank modifier is then used to increase/decrease certain things pertaining to the specific skill.
So, for example the Strike skill. This is a medium damage melee strike. The modifier for it increases damage output, and also slightly increases critical hit chance. I also have a 'Toughness' Skill that adds to constitution and therefore gives the character more health. In that skill's case it's modifier relates to how much of a bonus the character receives.
This system is quite extensible and can be limited/used in many different ways. I look forward to implementing more skills and spells. Now that most of the backend i wanted up for an alpha is complete, I will actually be able to work on game content.