Bungie included a short dive into how they make balance decisions, from how they think about a weapon type's position in the meta, to how they validate changes with playtesting. Read it in their blog post here

Weapon Archetypes

Fix mistimed reload animations for Drang and Zaouli's Bane such that ammo appears in the magazine at the correct time.
Increase Auto Rifle damage against minor (red bar) enemies by 10%
Increase Pulse Rifle damage against minor and major (red/orange bar) combatants by 12.5%
- Pulse Rifle range was closer to Hand Cannons and Auto Rifles, but had the lower damage os a scout rifle. This change should correct for this somewhat.
Increase Sniper Rifle damage in PvE by 15%.

Glaives

Projectiles
- Increase speed by 30%
- Increase PvE damage by 25%
- Decrease damage in PvP down to 125 for Aggressives, 113 for Adaptives, and 101 for Rapid Fires.
- Glaive projectiles felt too slow to be easy to use, making Impulse Amplifier a common necessity. In PvE they also didn't do enough damage to be worth using very often. The PvP nerfs are to make sure that the projectiles don't become too strong as they get easier to use.
Melee
- Reduce the delay before you can fire a projectile after a melee 0.75s -> 0.2s
- This was introduced to make sure someone couldn't use a projectile and a melee in one event, but it was too long and felt clunky to use.
Shields
- Shield energy now recharges at 1% a second when the glaive is held
- Damage resistance in PvP is now tiered, with the base resistance being 50% (as before), but only giving 30% resistance against primary weapons and melees.
- Shields requiring projectile hits to charge was done to reduce uptime of the shield which has a very high damage resistance compared to other sources. Ultimately though, it made glaives without shield charge feel like using half a weapon. This passive charge rate should give just enough that glaive's aren't useless when not hitting projectiles.

Exotic Weapons

Vex Mythoclast
- Increase damage against minor (red bar) enemies by 10%, bosses by 25%, and (when in linear fusion rifle mode) 200% against champions.
- Vex Mythoclast hasn't grown enough from the range and PvE damage buff in Season of the Witch, they're hoping to give it enough strength so it finds its own niche in PvE. They hope it can find a use as a sort of swiss army knife gun, useful in almost any activity.
Revision Zero
- Increased damage vs champions by 100%
- Similar reasons to Vex Mythoclast, but with less of a buff against champions because it has intrinsic Anti-Barrier.
Thorn
- Picking up a Remnant will now overflow the magazine, up to 40 rounds max
- Catalyst will grant an intrinsic +20 range, +10 stability, and grant additional range, handling, and mobility when picking up a Remnant or getting kills.
Osteo Striga
- Prevent the damage bonus latent to SMGs from applying to poison damage. Osteo's poison damage should now match the standard poison from Necrotic Grip, although still will deal an increased 40% damage due to being an exotic primary.
- Osteo has been dominant for too long, being far too strong for how easy it is to use, with less precision required and longer range than other SMGs. This specific change might not move the needle much, but it should be less of an outlier.
- They can't simply buff other weapons to the level of Osteo Striga because it would introduce extreme power creep, trivializing much content in the game.
Salvation's Grip
- Placed a limit on the speed at which crystals can shatter, preventing too many crystals from breaking on the same frame, which would sometimes kick the player to orbit.
Winterbite
- Increased detonation damage of the large projectile by 25%
- Half the range and damage of the self-damage aoe.

Class Glaives

All
- Grant 1 ammo when using the perk, so ammo is no longer required to activate the effects
- No longer passively drains shield energy when you special reload to activate the perk
- No longer deactivated by reloading or stowing the weapon
Edge of Intent (Warlock)
- Changed the effect of the healing turret to grant cures and restoration.
- Increased the AoE radius to 8 meters
- Increased its magazine size from 4 -> 5
Edge of Action (Titan)
- Passing through the bubble now grants bonus reload speed, handling, and a small amount of stacking bonus damage in addition to the overshield.
- Reduced the health of the bubble from 8000 -> 2400 to account for the improved uptime and additional effects
Edge of Concurrence (Hunter)
- Lightning Seeker now jolts on impact
- Reduced the direct hit damage of Lightning Seeker to account for the free ammo

Perks

Danger Zone
- A change was made to how Danger Zone works on rocket launcher, they are neglecting to say what the change is and encourage us to find out for ourselves next season.
Heavy Grip
- Accidentally was slightly increasing incoming flinch, this has been fixed.
Precision Instrument
- The enhanced form of this perk was barely noticeable, so now the damage bonus at max stacks is 30% (up from 26%)
Kinetic Tremors
- Pulse Rifle activation shots reduced 12 -> 11 (increased 9 -> 10 for the enhanced perk)
- Non-burst sidearm activation shots reduced 12 -> 8 (reduced 9 -> 7 for the enhanced perk)
- These changes were to make the activation requirements for the perk more consistent across the archetypes.

Future

Near Future
- Bow tuning in PvP
- Additional weapon tuning for Checkmate, aiming to promote a better diversity of weapons
Far Future
- Necrochasm will get a buff to the duration of the poison DOT it applies from the explosion. It will also get a new catalyst effect called One for Thrall, which will grant a moderate period of increased damage, rande, and aim assist after damaging three enemies in quick succession. Damaging an additional three enemies refreshes the perk duration.
- Buffs to Truth, Colony, DMT, and other exotic weapons
- Heavy Grenade Launchers will get a substantial inventory buff

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Sources:

Dev Insights: Season 23 Weapon Tuning Preview