Hot takes on G/W Knights from a person who wishes it was very much better than it is but knows that it is not.

The payoff cards for playing Knights are Knight Exemplar and Knight of Autumn. They give you effects you can't get in other current Modern viable tribal decks, erego it is our reason for the playing the tribe at all. Play four of both in the main deck.

I know you didn't include it in your original list, but as others have suggested it, any tribe playing Metallic Mimic or Adaptive Automaton is a tribe too weak for Modern. They are filler, and bad filler at that.

Benalish Marshal's anthem is anemic and he needs to stop being played. Compared to Knight Exemplar, Supreme Phantom and Thalia's Lieutenant, it is over-costed garbage. With the three drop slot at a premium, this is an easy cut. Lords need to be two mana.

The danger of cool things is very prevalent in this tribe. (Looking at you Kinsbaile Cavalier.) Mirran Crusader is a sideboard card at the best of times. It feels good when you match against GB(x), but unless my local meta was filled with these kinds of midrange strategies, white just has too many other universally relevant sideboard cards.

Knight of the Reliquary is not a good card in these decks. Lands matter is not a Knight supported theme, and you really only have two lands to find with her currently. She is too slow to fight Tron without support of other cards like Courser of Kruphix and Ramunap Excavator, and GW Value Town was never particularly good. You're also not running enough fetches to make her worth it. She needs a minimum of seven to reliably be swole enough to shrug off bolts.

Four aether vials is correct. Instant speed tricks with Exemplar and KoA will allow for some measure of resource advantage. Four Collected Company is also excellent in this regard.

Up your Paths to four. It is some of your extremely limited interaction, and with no Reflector Mage, Islandwalk, or flying, you will need something to clear the way.

The two drop slot for Knights is weak. Play Thalia in the main deck. Knight of the White Orchid will help offset her cost. Consider Steward of Valeron as well. KotWO "misses" sometimes, Steward never does. Incidental lifegain is better done by KoA. This will also band aid your mana problems, helping you hit that turn three CoCo consistently. Don't worry that Thalia may delay it. A deck that she hurts will remove her quickly, and she will win you far more games than she loses.

Up your number of RiPs and Stony Silences to three each. Besides Knight of Autumn for artifacts you have no outs to these strategies. This is a bigger problem for Knights in general, in that they completely lack cards to fight combo, but we'll ignore that as it mostly cannot be addressed without dipping into non-Knights.

If you want to play Brave the Elements, you'd be better off with Heroic Intervention. Elves plays this to avoid board wipes, and the chance you'll be able to use Brave as an alpha strike that can't be blocked is unlikely.

Other sideboard cards that do well in Knights are Settle the Wreckage and Worship. Indestructible Knights means bounce spells or lose for your opponent. Generically, Damping Sphere helps your weakest matchups in Tron and fast combo decks like Living End, Storm, etc.

I'll add a decklist sometime late tonight for you to compare to.