The problem you're detailing is that getting first strike is too effective because it allows you to wipe out the enemy before he can respond. If you nerfed weapon damage (as has been discussed elsewhere) the result is that your charging units do not wipe out the opposing army on the first strike. That means you can easily nerf charge (if you must) just by giving it a stun. If they attack after charging, they lose their next turn. Imagine how much fun it would be for those lightly armored spear-wielding troops to stand in for two rounds against the swarming attack of the enemy's front line.
I'm rather new around here, and haven't seen these suggestions before, but I like the general idea. Nerfing damage means more attacks needed to kill an enemy, and thus even powerful skills could exist, as they may not insta-kill opponents, and might also come with drawbacks if you try, like a stun. If the skills were still powerful enough to insta-kill, then you'd probably be steamrolling against an inferior opponent anyways, so it wouldn't really matter.
The reasons I don't like OP's Adrenaline suggestion are that it limits usage too much. Right now you have a theoretical choice of when to use the skills, be it on first attack, or as finisher or whatever, but with adrenaline in place you'd be disallowed the use in the start of the battle, and be forced to use the skills later on, and even then according to how your adrenaline happens to fill up. I would much rather have special attacks usable whenever I desire, but either with consequences (eg. powerful attack with stun), or as alternative attack methods (eg. instead of 100% damage on one tile, do 33.3% on three tiles). The latter type of ability could also be usable every turn, since it merely distributes damage differently, adding more tactical options, rather than more raw power.
