[QUOTE=Berethos;5372948]I assume this would be via some sort of tiered change that kicks in at certain levels but doesn't apply past that?[quote]
It could be tiered or extrapolated at each level for a more continuous change. It depends partially on what's easier to code, which only SE knows.

Having 10%, 15%, and 10% again at end-game just to have them last longer would necessitate quite a bit more rebalancing of content past when Gladiator is relevant.
I don't think I understand what you're saying here. Values should only increase with level, not jump back and forth.

Which, in trying to solve one issue you've introduced another, in that now the person who levels Gladiator has to remember that the same abilities that did 20% for 20 seconds, etc., now do half that for double the duration (questionable use at that level, not sure when you'd need cool downs that last that long, 10% or otherwise) but only in a certain level range, and potentially adjust accordingly, introducing a wrinkle into learning their job that only exists in a specific scenario that isn't even relevant to end-game?
Skill durations aren't changing, the longer duration comes from the PLD having more defense skills than GLA. PLD with halved or thirded effectiveness Rampart, Sentinel, Sheltron vs GLA with normal Rampart for example.

Sure, the numbers look like they work on paper. Consider how that would feel to actually play - not so simple to solve, now is it?
That's why I didn't change duration. It's harder to feel the reduced effectiveness of the mitigation skills than a change in effect length, especially if those reductions are only imposed in specific content. A PLD with reduced skill effectiveness would just play normally.