This came up in this thread but I thought it worth its own topic as it’s too important to be overlooked.
Currently there’s no way to discover how In Combat duration works. I mean you can’t even see it when not in combat as the timer is inactive. Once in combat the timer starts but normally you are too busy not dying to pay it much attention.
In theory you can tell how long the duration is by just noting when it starts and stops. But this is very hard to do accurately, to more than e.g. a half second accuracy. This therefore makes it hard to see what effect items have to reduce the duration. It’s only when VIT changes by 20 or more it becomes really noticeable.
This is a major flaw in the game, as normally it’s possible to immediately see how abilities impact the game. You increase your DEF you take less damage. You increase your SPD you go faster. ATT and DEX boost your weapon damage/speed, VIT and WIS boost your HP/MP regen.
Wismod is more complex, and varies by class, but you can see its effects directly in the info for your equipped ability, as you e.g. swap out different WIS items. You can similarly see how DEF affects IC damage threshold (and you can easily see its effects as you notice what it takes to put you In Combat).
What I would suggest is add the time to the popup panel so it is visible even when you are not in-combat. This means you can check it any time. You can see when it changes due to VIT items, VIT boosts from abilities and consumables. I.e. only a small change, especially as the code to draw something there is already in the game, just inactive when not In Combat.