How is Donnel bad? He can learn skills such as Armsthrift, Sol, Counter, and Aptitude and the main excuse is "he is too hard to train" but his growth rates are superior to any other character and it isn't even an Est situation because you get him very early. Proof that Donnel has better growths than Chrom. Here is the photo. Some might be mad that I made him a merc instead of a villager but that is what he will be for most of the game.