As much as I feel like TLI could seriously use a level cap for improving the combat statistics of your character, there are many people who would feel robbed of their progress and the endless cycle of levels I suppose is one of the inherent qualities of the game.
That said, looking at how spell slots, attack and defense statistics work I feel like the system would be better if it was percentage based instead of adding numerals to the final tally.
What this fixes.
Makes weapons, armour, and spells more worthwhile for later levels. As a character progresses the boon of their sword, or the difference expensing spell slots provides takes a nosedive.
Prevents a well equipped low level from becoming untouchable to another. They still get a boon to every roll, but not a invulnerability to all but the perfect strike.
I helps with situations where you might feel like there is no point rolling as you cannot exceed their defense bonus.
It makes great rolls even better, and poor rolls stay poor.