Ive broken most feats up into half-feats, and I find it becomes substantially easier to balance them. It then also becomes much easier to introduce new ones.
that is what I did also.
here is my take on it:
All are half feats: so you can get two of them instead of ASI or 1 ability and 1 feat;
Alert: cannot be surprised, hidden enemies do not have advantage vs you.
added;
Improved initiative: you gain +6 to initiative roll.
Actor: same as PHB version, plus added proficiency in disguise kit.
Charger: If you take Dash action and you move last 20ft in straight line towards an enemy, you can make one melee attack as a bonus action. Add your proficiency modifier to damage. If you have extra attack feature add double proficiency modifier instead.
Crossbow expert: ignore loading properties of a crossbow(you still need 2 hands to load a crossbow). You do not suffer disadvantage on attacks while you are in opponents melee reach.
extra attack feature as a bonus action gone and not coming back.
Defensive duelist: same as PHB, bad enough to be half feat.
Dual wielder: You can draw 2 weapons as one object interaction. You can dual wield 2 non light one handed weapons. Your offhand attack is now part of attack action with your main hand attack(s).
This prevents you from making adittional offhand attacks as bonus action.
added;
Two weapon defense: while wielding two melee weapons you gain +1 to AC. Extra free AoO per round with off hand weapon.
Dungeon delver; remove resistance to trap damage and you have a "half feat".
Durable: to have all people included without reference to their con score; you regain max HP from using your HDs.
Elemental adept: chose energy type: acid, cold, fire, lightning or thunder. You ignore damage resistance for that energy type with your spells and abilities.
added
Elemental master: requires Elemental adept; you can change any acid,cold,fire,lightning or thunder spell damage to the type chosen by Elemental adept.
Grappler: as PHB, half feat.
Great weapon master; when you score critical hit or reduce a creature to 0 HP with non light melee weapon, you can make one attack with that melee weapon as a bonus action.
added;
Power attack: when you attack with two handed melee weapon(or versatile weapon in two hands) you can take -3 penalty to attack and gain +5 to damage roll.
Healer: as PHB but instead of 1d6+4+max No.HDs, you heal 1d6+max No.HDs
Heavily armored: as PHB
Heavy armor master: as PHB
Inspiring leader: requires charisma 14; needs only 1 min of speech. affects you and a number of allies equal to your level × your charisma bonus. Gain temp HP equal to half your level + your charisma bonus.
added
Inspiring leader, improved: requires charisma 16, Inspiring leader: gain temp HPs equal to your level + 2×charisma bonus.
Keen mind: this blows; as PHB but add one skill or tool proficiency to it.
Lightly armored: as PHB
Linguist: as PHB, add proficiency in forgery kit.
Lucky: as PHB but only 2 luck points.
Mage slayer: drop advantage on saves and you get a half feat.
Magic initiate: you gain only 2 cantrips from chosen class.
added;
Magic adept: requires Magic initiate; gain one 1st level spell from chosen class. You can cast it once per long rest. You gain additional cantrip from that class spell list.
Martial adept: gain one maneuver and one superiority die. Die is d8 or what ever your class has if you have this feature. Can be taken two times.
Mobile: your movement does not provoke attack of opportunity from opponent you attacked this turn.
added;
Fleet of foot: +10ft speed. When you take Dash action, difficult terrain does not slow your movement.
Moderately armored: as PHB
Mounted combatant: bad and limited to be half feat.
Observant: as PHB, or add +5 to passive insight also.
Polearm master: when you make attack with any long hafted weapon with two hands(quarterstaff, spear, pike, halberd, guisarme, etc...) you can make one attack with opposite end as a bonus action. Attack deals 1d4 B damage. Use str for attack and damage.
added;
Hold the line: opponents provoke AoO when they enter your melee reach.
Resilient: as PHB but now half feat.
Ritual caster: as PHB but now half feat.
Savage attacker: as PHB but now half feat.
Sentinel: as PHB but drop the 3rd part.
added:
Intercept: when a creature in your melee reach makes attack against a target other than you, as a reaction you can make one melee attack vs that creature.
Sharpshooter: ignore attack penalty with weapons at long range. Ignore cover bonuses to AC.
added;
Power shot: when making an attack with ranged weapon, you can take -3 penalty to attack and gain +5 bonus to damage roll.
Shield master: as PHB but drop the 3rd ability.
added;
Shield Bash: when you make Attack action with your one handed main hand weapon, you can make one attack with your shield as a bonus action. Attack deals 1d4 B damage. Use str for attack and damage. And magical bonus to AC from shield is used as a bonus to attack and damage roll.
Skilled: gain proficiency in two skills or 3 tools. Can be taken 3 times.
Skulker: as PHB but drop auto hide if you miss with attack.
Spell sniper: as PHB but you do not gain an extra cantrip.
Tavern brawler: as PHB but after attack action with melee weapon you can use bonus action to make one unarmed attack, or one grab attempt.
Tought: you gain one HP per level. Can be taken 2 times.
Warcaster: as PHB but now half feat.
Weapon master: Gain one fighting style. Gain proficiency in one weapon. Can be taken 2 times.
In addition: if armor proficiency feats are still considered too weak, maybe you could get armor proficiency istead of one skill via "skilled feat".