I like the idea and implementation concept of Vigilant of Stendarr Improvements and Additions but these mods have some inherent incompatibilities with NPC Appearance & equipment overhauls.

I made some patches for other mods which take a bit of time since they are not direct conflicts in X-Edit but rather edits to various nested leveled lists, outfit records (needed some new ones), etc. Took more time than I planned to invest into this so figured they could save someone a couple of hours.

Would give this a quick read before installing; you may want to modify yourself a bit further using these as a base (or skip entirely).

ISC Patch  - carries over Immersive Sounds Compendium Edits for the Robed Armor 
Diverse Skyrim - just merges in NPC appearance and Leveled Lists; Diverse's NPCs are templated so will follow Improvement's edits to stats and inventory.
Modpocalypse NPCs (I use version 1 with vanilla hair) - just merges in appearance changes. Easy NPC or most patchers do this automatically but I'm accustomed to doing it manually
WACCF Patch - just sets the Robed Plated Steel Armor stats and keywords equal to WACCF's Steel Plate Armor (base mod stats are a version of vanilla)
WACCF Armor & Clothing Extension Patch:

• Restores the custom chainmail hood (has armor rating isn't clothing) over the vanilla Steel Plated Helmet
• For the spellcasters added by Improvement, restores custom Chainmail robes with enchantments (adds a version with an enchantment tracking what Improvements was doing). Leaves the Robes Steel Plate for melee and archers
  

Unplayable Faction Armors Patch - this one is core for me; the others I tried to make standalone but mostly built around this core idea:

• Unplayable Factions has four version of Vigilant Armor - Light, Medium, Heavy, Paladin. 
• I created 3 parallel sets in leveled lists which combine Robed Steel Plate with the Light, Medium, Heavy helm/gauntlets/boots from Unplayable Faction armor (replacing the vanilla steel).  Most melee Vigilants will have a 3/8ths chance for Light Unplayable Faction version, 2/8ths Medium, 1/8th each chance of having a L/M/H around Robed Steel plate. Basically some choose a more knight based look, others go for a bit more monk.
• I used Nordwar's custom weapons - 1H vigilant will always use Nordwar's custom mace; 2H will get Nordwar's (strong) 2H maces at higher levels but may use iron or steel at lower levels. No more glass, ebony, etc.
• Archers have a 50/50 chance of use a Light Robed Steel Plate or light Unplayable factions get-up
• Spellcasters are left with the robe setup.
• Level 5 (spawn late game) Vigilants get the Paladin armor (Exlusively - no robed plate)
• Level 4 Vigilants get the Knight (heavy) armor (Exlusively - no robed plate)
• 2H vigilant lose the shield custom which doesn't make sense for them
  

You basically get a blend/mash-up. 
Unplayable Faction Armors + Divine & Daedric Cloaks Patch - adds Stendarr cloaks from this mod you should use in addition to Cloaks & Winter is Coming (Cloaks & Capes probably very good as well I only don't use because it seems duplicative)

Based on which of these mods you use, you'll want to go into X-Edit and quickly confirm you don't want a "last mile" patch to tie it all together reflecting your preferences. My persona LO for these patches (they are all flagged ESL and don't cost your plugin count):

- ISC Patch
- Diverse Skyrim Patch
- Modpocalypse NPCs Patch (I want it to win any conflicts with above)
- Divine/Daedric Cloaks Patch
- WACCF Patch
- WACCF ACE (Armor & Clothing extension) Patch
- Unplayable Faction Armors Patch
- Unplayable Faction Armors + Divine & Daedric Patch

Depending on which you use you'll need to patch your patches (there's nothing I can do about this it's how the game works) as I can't make 40 plugins for every combination. It's just a high conflict area to combine appearance, gameplay, equipment changes from multiple mods. I for example have BUVARP as well which affects these thus have a patch which merges the changes from that mod with those from above.

The perk additions from original mod sort of looked generous combined with the stat boosts but I'm not trying to rebalance before I see some negative impact in-game (guys going around demanding Daedric artifacts and attacking vampires should be strong; stopping them doing that is for another mod I wouldn't install)

Hope this helps. Do whatever you want with this as long as you respect the original authors; thanks to all of them and Elminster & co for X-edit.

Other mods to make base game Vigilants more interesting:

Keeper Carcette Survives SSE (also adds Vigilants to towns it helps flesh them out)
Stendarr Rising - The Hall of the Vigilant Rebuild

and of course Vigilant 

Kaldewing has another mod which you may find simpler than all this if you own Creation Club/Anniversary Edition: Creation Club Enhanced Vigil of Stendarr

I just bought AE but am in no rush to activate it; I may revisit it in future and mix in that armor base. If you want to shoehorn the armor in quickly with a % chance to spawn while running Unplayable Faction armors add it to the leveled list [ DIS_Stendarr_Armor ]