I've replayed manual tactical battles and, using the exact same strategies/tactics/moves/etc., results vary from winning with nary a scratch to losing while doing almost no damage.  It's as if RNG = d100 (heck, or even d1000).

Why do I think this is a problem?  Because skill = (1-RNG)  ie  skill decreases as RNG variability increases.  If I win (or lose) a battle I'd like it to be because of skill (or lack thereof).  Some variability is necessary of course, but currently it's so extreme that skill is secondary.

Solution -- RNG = 10d10.  Not exactly this of course, but you get the idea -- less variability.