As mentioned about a dozen times already... Most players, when encountering "this character can permanently die", they simply restart the game to keep that character alive. Can it be done well? Yes. It can. Mass Effect 1. No, not with the Wrex Example. The Ashley/Kaiden choice.
When I played Mass Effect 1 for the first time, I was without internet. I had no way to google anything, no way to look up anything, it was just me with my choices on a raw and blind playthrough. I got to the point where I had to choose who to go back and help. The infamous choice where one of them MUST die. There's no way to avoid it. And the characters kick you while you're down when you get back to the ship for whatever choice you made. I lost one of my characters. I restarted, thinking I'd done something wrong. I tried again. The other character died. I thought I did something wrong again. I ran through every possible permutation of that situation and couldn't find a single way to get them both to live. I figured I maybe made the mistake much earlier in the game. RPGs don't kill of your characters by letting you choose! That's crazy! I let Ashely live and she definitely kicked me when I was down because the only reason I'd chosen her was for the Paramour achievement and I rather liked dating her. Her line to me? "Did you pick me because we're dating?" or something to that affect. Owch. Yes, I did Ashley, but you make it sound like... It was WRONG to make that choice.
So, I got internet back much later (I'd been playing freakin' tag with my provider for two months and they had lazy people who were unwilling to hook me up... I got two months free service because of their jerking me around, but I digress) and I looked it up. I was on a New Game + of Mass Effect 1. Making my second run through the game, and I looked it up to see if there was ANY way to make them both live. To my horror... No, there wasn't. I had to choose. That choice was permanent. Nothing I could do would save them both. One had to die for the sake of the narrative.
I have never made a more powerful choice in gaming in my life. It seemed so unfair to condemn Kaiden to death just because I didn't like him all that much or just because I was romancing Ashley. Those are stupid reasons to pick someone to die. It seemed so mean of me to pick Ashley over him just because I liked her as a character and genuinely enjoyed romancing her, having her around, and using her in my Squad. Was Kaiden's life really worth less than Ashley's to me, just because I was romancing her and I didn't particularly care for him?
I didn't have an answer that satisfied me. To this day, it is still something that makes me wonder if I made the right choice there. I even made a Femshep so I could romance Kaiden as some kind of means of redeeming myself. I could choose him over Ashley for the same reasons I chose Ashley. Maybe. I guess.
But, for me, that was powerful.
Fire Emblem? Not so much. "Oh, he died. Reload the battle."
If you are going to make a character death impactful, it needs to be absolutely necessary and irreversible. It needs to be something you cannot just reload the last save and "fix". Otherwise... prepare for players to be reloading it over and over again to keep everyone possible alive. Don't think they won't. They will. This is why Roguelikes usually delete your save the moment you load the game up. Because if you quit without saving or die... You lose your character and progress. Otherwise, you'd just keep reloading until you didn't die. Your character would lose value. Though, admittedly... I keep backup saves in Roguelikes so I can just import them back into the game if I die ~_^. Roguelike games aren't very good at spotting extra copies of a savefile somewhere else on the harddrive.