Langrisser vs fire emblem isn't really a good comparison, as they have different systems and tones, with langrisser being fairly brutalistic and realistic while fire emblem being more fantasy, though fire emblem can get a bit dark at times too as well, it rarely reaches the level of langrisser in tone, though both are tame in comparison to say, vandal hearts.
I prefer langrisser myself (like both however) but again it's not a good comparison, as they have different feels imo, it's like comparing final fantasy tactics/tactics ogre to fire emblem, they scratch a different itch imo.
You might want to give kingsvein a try:
Explore and reclaim the infested castle-city of Kingsvein! Ride into its depths on your trusty wyvern, and lead your customizable party of Knights and Mystics in deep tactical combat.
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It's a tactical rpg that's come highly recommended to me, i haven't had a chance to try it myself but the person who suggested it to me is a tactical rpg fanatic and loved fire emblem.
The dev of the game seems to make good tactical rpg's in general, checking their previous games.