I considered a system of learning different types of techniques and then combining them into a personalized martial art.
First off, you learn techniques from martial arts books; like recipes, each technique requires a certain skill level in unarmed. Also consider adding whole styles to books since NPCs aren’t in the best shape yet. Learning a style teaches you all accompanying techniques,
Then, assign each technique to an attribute. The higher your attribute, the more effective those techniques are.
You can then combine any number of techniques into a custom style. However, once you exceed a certain limit, you start taking penalties to your combat skills due to an “confusing” style.
Martial arts also have a “competence level”. At low competence, you take penalties to your combat skills. As you increase your competence level by using the style, the penalties are negated and eventually become bonuses.
When you change your custom style, you lose some competence at it depending on how many changes you’ve made.