Order Domain.
Because you are The Law. However, it's strangely reminiscent of a Warlord.
Spells.
Heroism not too useful as a low level buff.
Slow is nice.
Compulsion is a good way to generate lots of OAs.
Dominate Person Is another good way to turn the tides of battle in your parties favor.
Bonus Proficiency
Another Heavy Armor Cleric, because why not right?
Really should have gone the spellcaster route to differentiate it more from the various flavors of Paladin we have lying around. Or maybe even gear them into using bows, because the Law has a Long Arm. Yes I know the classes are different mechanically, but they should also look different and be in different positions of the parties formation.
Voice of Authority
Hot off the discussions of Warlording, here is a way to Buff your ally and make them attack at the same time. I believe this also works if you cast a spell on yourself, which could be really useful at lower levels in order to get the maximum efficiency out of your turn (Something an Order Cleric would be into on the RP side of things, one would assume), by doing an attack->Healing word-> Reaction Attack combo.
Channel Divinity: Order’s Demand
Damn. This has combat uses, obviously. But it really shines in social encounters against mobs of people. Really powerful for it's low level access and cost.
Order’s Dominion
This is the other thing that Diviners are good at. Clerics don't get access to a lot of enchantment spells. Way less than the number of spells Diviners can trigger with this, and nothing above 5th level. I don't really care for it on this subclass. Orders Judgement (the ability from the stream) was more interesting, and fun. Even if it was "Warlordesque"
Divine Strike
Because it's a warrior-priest. Meh. Force damage is interesting at least. I still contend it should be a caster-cleric, or maybe a bow-cleric.
Order’s Wrath
Mob Justice in it's final form. All your allies get bonus damage whenever you deal your Divine Strike damage to a target. This is quite different than what most clerics get, and I rather like it, even if I don't like the triggering ability.
Closing thoughts:
I'll say it again: This subclass should not be a Heavy Armor Cleric. To begin with, this subclass seems more interesting in displaying force than resisting it. And secondly, we already have quite a few subclasses who lead from the front, and this could be the perfect opportunity to introduce the kind of character who leads from the back.
