Your bonuses from skills and styles are capped at 100, meaning that only the first 100 points are used to determine bonuses, with the following exceptions:
Your current fighting style is applied as an uncapped percentage bonus to the attack, defence and damage of all your combat techniques. For example if your strike normally has +20 attack and +10 damage, but you have 400 in your current style, the technique will actually have a +400% (i.e. 5 times) bonus giving it +100 attack and +50 damage (you can see this full bonus on your combat table).
Spells work as above, except they use their appropriate magic colour instead of your style, with the bonus being applied to their range, ascendancy and power.
Your weapon skills are applied as an uncapped percentage bonus to the attack, defence and damage of your weapons, as per ‘help weapon’.
Points of Athletics over 100 are applied as a flat bonus, as per ‘help health’.
Note that if you are using an advanced or super style, the cap will still apply to the first 100 points, distributed as a 50%/50% or 34%/33%/33% bonus.