D&D 5E [Homebrew] Five refined combat pillar feats (latest rev)

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Previously I looked at a wide range of revisions to feats based on surveying how much they were being used. I've been refining and paring those back for my campaign to minimise revisions to core, including minimising additional concepts or text changes. If these feel robust, the next step is to fill out their number with at least one social and one exploration pillar feat of competitive value. All your feedback is highly appreciated.

Crossbow Expert
You ignore the Loading quality of crossbows with which you are proficient.
If you make a melee attack against a creature, being within 5 feet of that creature doesn’t impose disadvantage on your ranged attack rolls for the rest of the turn.
When you use the Attack action to attack with a one-handed weapon, you can use a bonus action to load and attack with a hand crossbow you are holding.

The design pillar here is that ranged remains worse than melee when in melee.

Defensive Duelist
When you are wielding a one-handed or Versatile melee weapon with which you are proficient and a creature hits you with a melee attack, you can use your reaction to add your proficiency bonus to your AC against that attack, potentially causing the attack to miss you.
If a creature misses you this way, roll an additional d20 with the first melee weapon attack you make against it before the end of your next turn. If that roll would score a critical hit, it replaces your attack roll.
Once per turn, when you roll damage for a melee weapon attack, you can reroll the damage dice and use either total.

This is designed to fill a gap for a competitive dueling melee weapon feat.

Dual Wielder
You gain a +1 bonus to AC while you are wielding a separate melee weapon in each hand.
You can use two-weapon fighting even when the one-handed melee weapons you are wielding aren’t Light.
Attacks you make with the melee weapon you’re holding in your other hand, as part of two-weapon fighting, don’t use a bonus action.
You can draw or stow two one-handed weapons when you would normally be able to draw or stow only one.

This is designed to double-down on the panache of dual wielding: allowing it to fit better in the action economy with class features and spells.

Mage Slayer
You can make an opportunity attack when a creature that you can see within your reach begins casting. If it hits, the creature makes a Constitution saving throw. The DC equals 10 or half the damage taken, whichever number is higher. On a failure, the creature’s spell fails and has no effect.
When you damage a creature that is concentrating on a spell, that creature has disadvantage on the saving throw it makes to maintain concentration.
You have advantage on saving throws against spells cast by creatures within your reach.

The design pillar here is that melee should be able to double-down versus casters, once in reach.

Sharpshooter
Attacking at long range doesn't impose disadvantage on your ranged weapon attack rolls.
Your ranged weapon attacks ignore half and three-quarters cover.
Once per turn, before you make an attack with a ranged weapon that you are proficient with, you can choose to take a −5 penalty to the attack roll. If the attack hits, you add +10 to the attack’s damage.

The design pillar here is that the best damage from ranged must be meaningfully less than the best damage from melee, because ranged damage comes with benefits that factor against melee damage.