Justicar of Muir Prestige Class for 5e?

I've been working on my conversion for Stoneheart Valley, and was considering trying to make a Prestige Class for the Justicar of Muir. I wanted to know if anyone's done something like that already, and if not, what they'd do for that part of the adventure. 

 

My first thought is that it lets you summon weapons, armor, and shield, a la an expanded Pact of the Blade warlock ideal.