I agree. Mighty Deed is much better than it was rated. Paladins are the kings at killing things early in fights. This allows you to go KO a minion, buff the party and then charge onto the next minion to repeat.Expeditious Retreat work nicely with Find Steed.
Conjure Volley, while not gotten until 17th, is a DEX save vs. your CHR-based DC, it does not need DEX or attack rolls.
To me the fact that this can happen every round you meet the conditions with no per-rest limit, and is affecting CHR creatures, so probably 3-4 when you get it up to 5 later on. That's pretty amazing. Paladins don't have a lot to deal with hordes, but the benefit off a horde is that you can drop someone every turn. So this helps them shine in what is traditionally a place they are only so-so. And it's useful to some degree the rest of the time.
Plus it has synergy with the CD for an extended crit range.