Some quick thoughts on stats:

Reactions are tied to skills that use reactions (like dodge, for example) and also are tied to resisting transport runes. So I'd say reactions are okay.

Wisdom isn't a terribly useful statistic. It's tied to total mana, but total mana isn't a very big deal with mana pets and powerstones. There were rumours that wisdom was tied to the potency of attack spells. If that's really true, wisdom would be valuable.

Endurance ties into fatigue points, so it is useful. However, currently fatigue point regeneration is tied only to constitution. That makes constitution quite a ton more important than endurance. It might be worthwhile to even that out a bit. Your idea for having combat prowess affected the longer a combat goes, modified by endurance, could work well.

I don't currently have any big ideas for this, I just thought I'd share some of what I know about statistics in case you ever get a chance to address them.