The story characters, only learn the first 3 abilities for each weapon forte they have. A few of the special characters, learn 5. The only way to get them more is to teach abilities to anyone who doesn't learn them, is class world, and it costs 10x more mana by default, but can be lowered 45% if you clear all the blocks out of each level. The last 2 skills for a weapon are learned from the portal on the 10th floor of class world, where you have to clear out all the blocks to make it appear.
Rule 1. I am always right. Rule 2. If in any case I appear wrong, refer to rule 1.