Hect

I tend to use a combination of units that I like and units that are considered viable. Though, most of the time, even the units that are considered weak by other people turn out to be some of the best units in my roster. Eddie has done well so far, so I didn't have any reason to replace him with Zihark. But I snatched his Adept from him, haha. I also used Mia over Zihark in Path of Radiance. (I feel like female Swordmasters are quite rare, so I was really keen on using her, and she didn't disappoint. Many people may consider her worse than Zihark, but I didn't really care all that much. Still beat PoR just fine.) Perhaps I should've given Zihark a chance, ah well.. not like I'm saying that I don't like the guy. He seems to have that Swordmaster..esque "chill dude-attitude" while managing to be an overall nice guy and I really like that a lot. But in the end, I can't use everyone. ^^

Yeah, Zihark is a Navarre through and through. He is an intetesting character and unit, but I tend to prefer training up base class units into their final forms. I've never been much of a fan of pre-premotes. I didn't use Seth in FE8 or even Camilla in Conquest (shocking, I know). I just prefer growth units, like Ests, Lords barring Sigurd, and Merrics. It basically boils down to playstyle choices.

Mmm yeah I'm not trying to tell you how to play the game, you do you. I'm sure Edward will serve you well in the future, he generally does for anyone who trains him. I actually applaud you for using the characters you like, though you're spot on about not being able to train everyone, particularly so in part 1 of RD. You really just want to pick about 4 characters optimally (not including Micaiah and Sothe) and exclusively train them. For me that's usually Nolan, Aran, Zihark, and Jill. I think the view of people who go gung ho for using nothing but the best units in this case boils down to Edward is a good Swordmaster that you need to train, while Zihark is a good Swordmaster that you don't.