And I just found something. You can edit your skills with the .sol to master them.
Location is MARDEKv3__sg_(Your Save Number).sol -> PCstats -> (Character Number) -> learned -> Reactions
In the 'learned' section are the skills you can use in Battle, the attacks and such.
In the 'Reactions' section are all the others, increased weapon damage, decreased damage taken, and others like that.
To edit them, find the one you want to change, I'll just do DMG+10% as an example, it is located in Reactions -> P_ATK. Expand the DMG+10% to see the variables 0 and 1. They will each give you two options when clicked on, the Number Name and the Number Value. In '0' you will find the Number Name is 0, obviously, and the Number Value is the amount of uses you have for the skill, in this case DMG+10%. To master it, set the Number Value in '0' to 10 and save, when you load, it should be Mastered. Also, if you look in the '1' variable under DMG+10% the Number Name is 1(again quite obviously), and the Number Value will be 0 or 1, depending on if you have the skill equipped. 0 being unequipped and 1 if you had it equipped.
If that doesn't work to master them, just set it to 1 under what would normally be required, such as 9/10, then once you use it once, it will master it. That is the method I use.