There is nothing "tactical" about the tactical battles. Basically all your guys are on a grid, all their guys are on a grid. There are no obstacles or impassable tiles to create choke points or anything like that. Most of your spells are single target, infinite range, deals 1 to X damage where X = your INT. Melee attacks deal 1 to X damage where X is your attack rating. Defense reduces damage ranging from 1 to X where X is your defense rating.
The wide number ranges make it hard to guarantee that any given attack will result in a kill, and it's especially frustrating when your spells roll low because you only get back 1 mana per game turn. So blowing 10 MP in a fight is rarely worth the price.
When you research warfare tech you can make groups of units that all stack together on the same square. Instead of 4/6/8 guys with individual stats, their stats are merely added together. So basically, 4 peasants = jaguar warrior, 4 axemen = niefel jarl, 4 knights = prince of death. It's pretty crazy. You spend all this time leveling up your sovereign so that he has 40 HP and a whopping 20 attack, and then a couple turns later you can just crank out unlimited numbers of 150HP 300 attack units in all your cities.
That's the gist of it. I bet one day all the units, equipment, spells, and special abilities will be modded to make tactical combat as good as it was in Age of Wonders oh 17 years ago...one day. But not today.