I'm a casual tactics game fan, and for me it feels like these games sit in two categories:
1. If you make a single mistake at any point in a battle, you are doomed.
2. You can recover from mistakes and therefor feels too easy sometimes.
Fire Emblem is #2 for sure. The difficulty in Fire Emblem for me is keeping your team equal in levels. An over leveled unit will handily take on anything that comes at it, and an under leveled unit will struggle against more than one enemy at a time (and often against just a single enemy as well). So making sure the entire team gets some attention becomes the challenge. Every FE game I have played is relatively easy for quite some time, but if you let some characters run away with all the XP and ignore others, eventually it will catch up to you. Team management is a long game. Every FE game is a little different in how it does it, but you can't always just grind your way out of a problem. Hard mode on the latest game, for instance, has finite battles, so you can't just spend time grinding up characters you've goofed up on.