So, i just finished final fantasy 4 in DS, and i enjoyed it most of the time, but one thing was bothersome for me. Some characters, from time to time, get out and get in on my party. Mostly, this is used as a way to tell a history about someone dying for us and all that, or just betraying us when we trusted them so much. The problem i have with this is that, sometimes, they just screw over my strategy. I invested some money buying them equipament, and even healing them when they just so easily died with one hit. What is worse, is that some of them are replaced for a character somewhat underleved, compared to the rest of my party, and them i can't shake the feeling that this guy is just making waste my time, and is no use for anything but dragging the gameplay behind.

Yes, i'm taliking about edge. This guys is a pain on the ass, he was so weak when i first got it. And since he is meele, i have no option but put him on the from row, where usually he died again and again and again, and did'nt matter how much i grind, because the party would always be ahead, and since he is the weakest(even when he had more hp, he died more easyly than freaking rydia), he was usually the one dead after the battles, which mean that he didn't got exp like the other, putting him even more behind. I could not shake the feeling to that yang was a much better partner, and he could take heavy hits without effort. When i discovered that he was in fact alive, i got sadder because i could'nt just get rid off edge and put yang there.

The constants betrayal of kain where just as bad too, since i used most of my money to get him a fancy armor, just to see it wasted in the end of the chapter. Since i had no option but play with him. I could not just put him aside, i had to use it, even if i never trusted him in the first place.

I started to wonder if this happen in some other heavily history based game too. Your gameplay is disturbed with some event that will not really add something worth to the game mechanics. In those times, i undestand why some games really don't bother with a significant history, since this will problably mean interferences on the main gameplay.

hmmm...from my experience Edge was alright, he was far from a Cecil, kain, and Yang but got the job done when I used him, at least he was more useful than Edward -_-

Edge is an attack/magic/support character, so if you expect to throw him in the front row and be a power character like Cecil or Kain, then you're going to be disappointed. With spells like pin, he can stun enemies, or with image he can completely negate damage, which at that point is the time you can put him in the front row.  The speed that Edge has compared to Cecil and Kain allow him to take more turns, so the amount of damage that he does will be somewhat comparable.

When you get Edge, you'll want to put him in the back row with the most powerful long range weapon you can acquire. You'll take off a bit less damage than you would with melee weapons in the front row, but your defense will be doubled. So keep Cecil and Kain in the front row, Edge, Rydia, and Rosa in the back row. Once you get to the end of the game, keep Edge with the best long range weapon and Muramasa(or Masamune, I forget which is stronger,) and leave him in the back row.

*edit*

If you ever play Final Fantasy 4 The After Years, which the 10th chapter is amazing and is what makes the game, Edge is the best DPS melee character in the game by far.  Deals some of the highest damage per hit and  is way faster than every other character in the game.  His only weakness is lower HP and defense than the heavier characters.

I confess that I felt most of the edge's spells were pretty useless, since even when i used a element advantage agains some enemies, his attack did more damage, and i tried to save all shurikens for final boss.
i would not put kain in the front row because i only use its jump, since do more damage and is not affected by in which row you are, and here was on wait for his tunr, he also took less damage. This is problably which made possible my victory, since before the final jump, all my party were dead and only kain was alive, with 1hp! The fellings... But yeah, even if the autobattle system gave me divisive feeling, for me, it is the best final fantasy that i ever played.

This is honestly one of the things I loved about FF IV over any other FF game and partly why it's my favourite in the series. I find it easier to switch up my strategy using the characters given than constantly switching costumes or characters in my party (ie. FFV and FFVI respectively) to find what works. That's a lot more time consuming and frustrating. I'm not a creative guy, so I like the game guiding me this way. The bosses, which are generally the only hard part, are kind of designed knowing which characters you will have at that time, so I always know it's manageable to beat them with who the game gave me. I admit I never liked Edge much either, but I never had as much of a problem as you seemed to have had in having him die constantly and not be leveled up enough.