Great chip damage units?

This guy's my favorite AoE damager. Not only can he soften up the enemy team, but he's great for training new units and he's a pretty incredible physical tank as well. Don't expect to be killing things with him, usually, but he'll make it super easy for the rest of your team.

Any of the healers can run this well, but not really any of them can be a physical tank quite like him, either, so he's a good choice for it.

I use both Jacob, and healers (Serra and Slide).

Jacob:
+ have good raw damage (I have +atk IV),
+ decent speed
+ exteamly good against mages
+ super fun to use :)
+ Def/Res debuff
- squishy
- expensive to build
- rare
- cant handle bulky distant counter units

Healers with pain
+ Enemy cant counterattack
+ Heal
+ Common units
+ Stats dont matter that much
- unless given wrath staff dont do much raw damage
- need help from other units to finish off
- cant equip posion strike

I have this Jaffar and I know him as the "Health Debuffer", he does 20 extra damage to his target and 24 damage to any enemies within 2 spaces of the target. It takes the 200 Divine Dew to get the weapon upgrade, but if you're looking specifically for a chip damager, I'd say it's worth it

You're headed in the right direction. The combination you're looking for is pain+ with double savage blow or Jaffar's refined weapon with double savage blow. Jaffar I would say is the more aggressive option due to the 7-point defensive debuff that his teammates can convert into more damage, but he is significantly less tanky than most healers and doesn't heal the team. You could also do smoke dagger (Saizo) double savage blow to shut down their offense, but the chip damage is significantly less.

One other option which can potentially do even more damage (but not against units with mixed bulk, who are probably the ones you most want to chip down) is growing wind Felicia. I suppose Ares would work too, but Felicia has the unique ability to target whichever defensive stat is lower - including on an AoE special, and if you refine her prf for the effect, you're virtually guaranteed to charge up the special after combat with a mage on either phase. You can stack savage blows on her for added damage like with any other option. Ares will be better at spamming it, but he won't ever be able to target res and he'll always be in the splash zone for growing wind, which might mean he hits a smaller number of enemies on average? Not saying that from experience.

As to which healer, I suggest looking at a video by Lu Bu Feng Xian who really likes strategies involving pain+. It's all about healers.

From my own knowledge, I'd say cavalry healers are especially good due to their mobility (will be very annoying for the enemy) and Azama, because his attack is so bad that it's his best way of doing damage (also, he's mind-twistingly tanky and comes with Martyr+, so great base kit). Maria's pretty good too - rather small attack stat, but lots of speed so quite difficult to double and decent numbers in both defensive categories. You could also look into Genny, who has a lot of brute force and runs the close counter + vantage combo well to clean up the enemy army; similar situation with Elise, who's on a horse. I personally prefer to do the vantage killing with +atk L.Robin, who has adaptive damage against ranged units and can take a hit or two more easily, but this is a matter of style.

Have fun savage blowing the life out of everything :P

Healers with Pain+ with Sav Blow 6 or Jaffar with the same skills should do the trick.

While there maybe better units for it (definitely a dazzling pain healer to guarantee avoiding counter attacks), I'm quite partial to my Kagero. Poison Dagger tends to decimate many popular units (L!Ike, Fjorm, Nowi, etc.).

Jaffar is the best to it. Every other healer with pain will do a just about job. To increase chip damage just put growing flame or growing wind for insane chip.