Not a real support class, but offer a lot more damage than anything so far down a support tree. It’s nice to be able to kill some things on your own.
The only other class that I can think of that comes close to the damage a Chaplain can do with auto attacks at C1 is Druid (and maybe Bokor since Effigy has no cooldown). Each swing with Bless, Sac+Last Rights and Aspergillum effectively hits 3 times. One for physical damage + Bless, 1 for Sacrament(which is buffed by LR) + Bless and 1 for Aspergillum + Bless.
Plus Deploy Capella allows you to buff people with all your buffs with 1 cast. Just place it in an area that is easy to run in and out of on certain fights and you get a lot of use out of it.