Like the title says, which units or characters seem like they need a bit of tweaking to get them back on the battlefield, and more importantly, why? Either their rules are outdated/broken, they are overcosted, or the army just features something else that totally eclipses what this unit brings. Also, how would you go about fixing those units so that they become viable again? Not become overpowered/must include in every army, but nice and balanced so that players may start using them again.
Rather than just listing units (which I've seen done in past threads) i'm trying to get a better sense of why they are bad, and brainstorm ideas on how to correct them.