Impressive work! Let's dive in...
Thanks!
Actor
Interesting the addition of cantrips. It makes sense to me that in a fantasy world, spies etc might have picked up a few cantrips. First glance, I like the idea.
I thought so, too. Message and Friends are less common, as well, generally not powerful, but fit the "Spycraft" idea you had and add some more flavor. This might cause them to be used more, and more creatively.
Armor Master
I quite liked the possibility of adding Smiths' Tools here as a ribbon, but I know others felt that was giving too much. I can attest to characters moving between armor types in my campaign, so in time this feat could benefit a character in both modes.
Yeah, I think this is well balanced. The switch between Medium to Heavy isn't a major impact, and it works to say, "You are wearing armor, so you always have some benefit." A character can go back and forth depending on their needs. Thematically, they seem to work together. Keeping the +1 ASI also offsets any need for additional proficiencies.
Athlete
My only complaint is that the climbing buff doesn't do much for Thief, which is the archetype you'd otherwise expect to want this. Hence I switched to give the +10' speed benefit similar to Mobility. I didn't feel there was any issue with having two feats that did that. Resisting Exhaustion is a really great idea, I might steal it. My only concern is perhaps this feat is bit baroque. Imagine you cut the prone, climbing/swimming, and jump speed benefits, and just give a speed increase: tidies it up immensely.
Hm. I like the idea of an archer in the trees, which a climbing speed helps. And I do like keeping the +10 movement in Mobile, just because Mobile is a great feat and I want to leave it mostly untouched. You're right that this isn't as perfect for a rogue, but there are other feats that a rogue could appreciate, like Skulker, and having multiple good feats to pick over your career is cool. (Note that I said "good" feats. Multiple feats that are all needed for a simple concept is poor design, but if each feat is a solid option and yet choice is required, that is good game balance.)
Brawler
I'm not sure how the reaction plays out. They strike you, reaction to grab, you strike back with advantage... does this work with polearm? It might need to be within 5' and if they miss.
Note that you don't have advantage until you are already grappling. I like the miss idea. If you were made large, you might have a 10' reach, so we want to retain that. How about:
"When a creature within your reach that you are not grappling attacks you and misses, you may use your reaction to attempt to grapple the creature."
Crossbow Expert
Could need a renameI dislike the 2H ranged use with a shield. I guess we're thinking pavis, but that should come with a movement cost or something. Perhaps "If you don't move during your turn, you can..."
Not sure which is better. They're both fairly complex. I tend to think about three abilities is the most to stack on one feat.
My intent is to make this a Ranger feat. Rangers have shield proficiency, but frequently that use two-handed bows. Likewise, they have spellcasting to support their martial abilities: lots of these are verbal only, but it seems like it would be nice to boost them. They could of course pick Warcaster, but that seems off-theme.
I was trying to strengthen this feat in a different direction from the original. The new wording nerfs the close-range benefit to once per turn, so I added the option to run away as a bonus action: Archer caught in melee makes a distracting shot and runs for his life.
Similarly, the crossbow as a bonus action with +Dex to damage and Archery fighting style was nerfed. Now the +Dex would only come through the Two Weapon Fighting style, so you only get one or the other unless you multiclass or pick up another feat that lets you do that.
This blocks the SS/CEx combo, but then in weakens the base feat: adding in the the bonus to shield use and spellcasting seemed a nice benefit to make it up.
I also tried to remove/clarify with version 2 the need for a free hand for reloading weapons with the Ammunition property.
If the shield benefit is too much, what if it was limited to "Your shield hand is free for firing two handed ranged weapons and spellcasting. When you use this benefit, you lose 5 feet of movement from your next move."
On the rename: I agree. I kept it this way just for clarity and alphabetical consistency at the moment.
On limiting feats to three abilities: I agree with that, too, although there are several more lengthy PHB feats. Any recommendations for simplification will be gladly considered.
Defensive Duelist (includes Dual Wielder)
I like adding the DW abilities here. I dislike limiting the defense effect to finesse. Rapiers, rapiers, rapiers, rapiers, and oh golly I think I'll use a rapier. I was looking for one more ability to add into my Duelist feat. Maybe DW is it?
Yeah, adding the "light or finesse" benefit helps it a lot.
Dungeon Delver (includes Keen Mind and Observant)
I like the Keen Mind advantages going into this, as it makes sense that these bonuses connect with delving. Makes me want to rethink my version! Initially, I felt the Keen Mind stuff was more Spycraft... but maybe this is better.
I agree. It seems like Keen Mind fits with Dungeon Delver very well. Keen Mind on its own is pretty much pointless, but as a dungeon exploration feat, it works nicely. I thought similarly about Observant, and split its benefits over a few feats.
Elemental Adept
Hearks back to 3ed caster feats. You know... this is probably better than the RAW EA feat. I guess they didn't reprise them because of bounded accuracy, but this looks narrow enough to be okay.
Oh yes, it is definitely better than the RAW feat, which I felt was too narrow. This gives a +1 ASI. I saw no reason not to expand the damage type options, especially poison, even though they aren't strictly elemental, but I did leave force out of the list intentionally: if you do meet a Force Dragon, this feat won't help you!
Furthermore, the reroll mechanic had weird side effects like making spell choice matter based on what size dice it uses, which is a bit weird. Giving a straight +1 to whatever spell you are using seems easier and more generally applicable. But it is still only on a specific damage type. A full +2 ASI would give this benefit anyway, and more, so dropping down to +1 ASI, retaining this benefit, and dealing with resistance/immunity but for a single element seems balanced.
Great Weapon Master - v1
As you know, I like this.
I like it, too!
Great Weapon Master - v2
This feels a bit less exciting than the original. +4 for -15% might not work out... (original is +10 for -25%). What I'm saying is - don't forget the excitement value of the original.
It is less exciting, which is unfortunate, but it is a lot more balanced. This version stays balanced/beneficial for a fighter with four attacks, improving with more attacks with advantage. The once-per-turn version, on the other hand, gives a power boost that is much greater, but only to single attacks. I think that I prefer the once-per-turn version, too, as it applies to many more characters, but this second version is better if scaling with multiple attacks is the goal.
I have to get on with work, but will revert about other feats later. One last note
I look forward to your continued feedback!
True Strike and Blade Ward
Could be right-minded. For sure those cantrips are nearly worthless in their current form.
Absolutely. My implementation may need to be refined, but these cantrips do need some help. Even so, they did not fit well with my "Cantrip Master" feat, so I felt they needed separate treatment.