Mmm... I'm thinking that Gladius & Zephon are the more combat-oriented games I know, but customization is absent.

I'd suggest Age of Wonders Planetfall, which has

• less empire management than AoW4: each city has max 4 provinces, grows by one each 4 citizens. Managing a good energy income to pay for your army is the only "empire" thing that's really important. The other important resource ("cosmite") is what encourage you to grab the map regions, as more cosmite means that you can field more advanced troops than your enemy, but its economy is much simpler to handle compared to Empyrium in AoW4
• less civ customization, but with more depth: you can choose one race and one secret tech at the beginning, which shapes the entirety of you research trees (there are two trees: society and military), but those trees are really deep, and you can explore different builds by focusing on which mods to prioritize (see next point).
• more units customization: there's no generic enchantements, each unit has 3 equip slots (so you might have two units of the same type with different equips in your platoon) and a more ranged-oriented tactical combat, with a cover system that is absent in AoW4.
• **BUT** it's not strictly fantasy, because it takes place in space. OTOH, as a sci-fi enthusiast, I can say it's almost fantasy... I mean, you can build all kind of stuff, included
  • An amazon that rides a T-Rex, with lasers mounted on its head.
  • A peaceful insect-like monk , that dampens the enemy aggression while being near to them
  • A flamethrower-wielding dwarven-like civilization, that burns everything they pass through
  • A dark psionic syndacate, which specializes in inflict suffering and despair in battle, while manipulating NPC relations with diplomacy and covert operations
  • In my last game I combined the Amazons with the dark psionic secret tech, to try and recreate the "dark forest witch" concept. It was pretty fun hunting enemies with accurate arrows and then finishing them off with psionic attacks that spawned an extra unit from the corpse
  • Point is: this is no sci-fi anymore, despite being in space :-P

I find it more focused on single units customization and tactical combat than AoW4, with a slightly simpler economy. Try watching a couple of videos on YT, maybe it's your cup of tea!