How to tune all skills of players, clans, fishermen, etc.

For editing skills you need to pass in:
Path - gameserver\data\skill_tree\

The list of files for editing:
fishing_skill_tree.xml - fishing skills. There it is possible to change the prices and so on
normal_skill_tree.xml - skills of all classes, what books are necessary for studying, a stake in SP
pledge_skill_tree.xml - Clan skills, their cost in RP and RB eggs and so on.
skill_enchant_data.xml - sharpening of skills

You can add to these files any skills for clans, players, fishermen and so on. Everything flexibly and configurable.