Ah okay, also as others have said, may need to work on the intro. Personally I had no problems going deep end first, but as an old hand at Fire Emblem I could manage fine. New players maybe might suffer.
Dunno if it helps, but here's an idea. Try fleshing out the intro by adding a CG showing our Merc King, could help with engaging the player before being thrown into gameplay. Attach a short starter battle (4-5 units on each side max, no mage on the enemy side since they can wipe you early on) onto the intro, an ambush on the road to the first town with everybody within attacking reach on the first turn. Make sure you skip the stage setup screen, the starter locations being preset with all units set up so the enemy closest to it is weak in the weapons triangle. Put some of the starter information in there, like movement and attacking, but don't introduce the weapon tree concepts or the terrain concepts until the town mission. Just a nice and easy battle to ease some concepts in before going full ham on the Town battle. Make sure to add a mission setup tutorial (explaining positioning and Convoy) as well before the Town battle since that's currently missing.