TEAM COMP & YOU. 

Bonded Shield bot + Levin Sword unit is absolutely optimal on every team. Like you said, you can just mop entire sections of maps with minimal unit cost. It's the best way to use fun builds/bad units because you really only need that Bonded Shield (appropriately abbreviated to B.S.) pair to beat the game. Alear/Framme Martial Master + Anna/Chloe/Pandreo Mage Knight will carry every Maddening run without thought.

And I forgot I used yunaka early on but her damage fell off so I stopped using her

Five-sevrn man team comp being god tier of course. Multiple engraving on weapons. Maxing weapon upgrades. Maxing sp skills. And having 250k after chapter 26 feels so good

You keep on mentioning that Paladin is a good/solid/decent class, but no one ever explains what the role of a paladin is in team composition. Archers take out the fliers and contribute chip damage. Mystics/Mages take down the armors and anyone using cover. What the hakes is the Paladin good for? I understand stat-wise they are good ... but for what purpose??

I have my team comp it is kinda bad but yea. Alear is bonded shield. Framme is staff not and chain guard. Louis is my main tank he has resolve with lance power 3 and on erika for more damage and better tanking. Jade is my ike tank she does worse then Louis but she tanks res better. Diamant is filler. Anna is a warrior with hero's axe who can get money. Ivy is also filler and has decent dex to use grasping void. Pandoro is another staff bot and some chip damage. Chole is my main attacking she has heroes lance plus 5 with marth engrave she is also very fast and can double most foes.citrinne used to be decent but she fell of so rip citrinne. Dancer has camilla with canto and qt and finally Alfred who used to be on lyn after all speed takes he got to 35 speed so he double and maybe crit but I put him on sigurd and moved lyn to ivy because ivy was a bit slow so yea thats it I know it's not the best but this was my first run on hard mode so take it with a grain on salt

Amber be better as an axe General or Warrior, both play off his high strength, General can be more independent especially with Tiki ring on him so can healing by waiting, and engage for a bunch of extra stats like Roy. Axes because of his build and hit passive, plus more might so he can hit even harder. Going to try Warrior Clanne, Sniper Jean, and Berserker Madeline for fun; also want to try Royal Knight on someone because I never used the class and it is pretty much has the growths of Griffin Knight except no flying (which could be beneficial for Royal Knight) -5%speed +5%hp +5%def +5%res [compared to griffin knight] - thinking either Framme or Jade as a Royal Knight. Dire Thunder Lindon could be fun with a crit+hit engrave since thunder would guarantee his +20 crit passive.

you want a balance of tanks, supports, and damage dealers Sages are good because they are a hybrid of damage and support Framme is very easily to turn into a super carry Hortensia just give her 5 staves, her having a tome is a waste, add on Rally+ if you using DLC rings Game would be easier if you had real tanks, General is the only real tank class in Engage, do wish they would add more tank and support class variety for the future (at least they added Enchanter and Mage Cannoneer for 2 more support classes, which will roll over to the next game). ~But imagine something like a tome General, this by itself would make Surge magic a lot better and maybe can add in Nosferatu, but it cannot follow-up which makes it better for a slow attacker. As well as add in a tier 3 version of Surge to the game. ~Maybe something like a shield basher class where it will equip a giant shield that each shield cannot follow-up, always break swords, lances, and axes, knock away enemies by 2 spaces as a weapon effect and when enemy phasing each shield will have some kind of benefit i.e. reduce damage to adjacent allies, grant bonus res, grant bonus armour, negate the first ranged attack, etc. and unlike smash weapons, the shields will be low damage and cannot crit (how could you crit with a shield?). ~Lead into that, a mage bruiser class that can equip tomes and shields, less damage than something like a Sage, but more damage than the shield basher and be a hybrid of sometimes tanking a few enemies and sometimes making kills / cleaning up kills.