Final Fantasy VII Remake Weapons

Cloud's Swords

Barret's Gun-arms

Tifa's Fists

Aerith's Staves

So in the original title, you got weapons over time, and basically discarded the current weapon for them. This has kind of been a thing through the entire series, with a few exceptions. Well that idea is gone in Final Fantasy VII Remake.
In Remake, there is a kind of level up ability for weapons. This allows you to unlock and further progress into new capabilities, attacks, and defenses. You can now literally go through the entire game with the Buster Sword if you so choose.
In the menu, go to Upgrade weapons. Next select the character you want to see. Finally you can select the weapon you wish to upgrade.
Here you will be able to unlock all manners of new abilities, and stat increases. This is done by spending skill points (SP) to unlock the Upgrades on the Cores of each weapon.
And with this system, there is weapons that go more physical or magic centric. And even with those, you are not on a singular line of upgrading. So you can go in whichever direction works for your play style. You can even skip through the available levels, without finishing the previous core level.

Acquiring Method	SP Gain
Level Up	5 SP
Manuscripts	10 SP

There are only two means of gaining SP for weapon upgrade. Leveling up and finding Manuscripts. You certainly want to get weapons upgraded. So you want to do some grinding for sure. As SP is independent for each weapon, do not be afraid to
spend as much as you can to increase their power. And with the customizable ability, you can choose the path in which you want the weapon to follow. Magic, Defense, or power dependent on the base weapon.
Every character has what's called a Weapon Level, and as it increases, you will unlock Sub-Cores containing more skills to unlock to keep powering up your weapons.
As you get more SP from leveling or manuscripts, your weapon's Level will go up. As mentioned, every time a character levels up they will gain 5 SP. But even capping out at level 50, you will only amass 216 SP. This of course is where manuscripts come into play.
In order to unlock weapon Level 6 for each weapon, you'll need that character's SP to hit 250. This is where the manuscripts come into play.
Only 3 manuscripts/character are available on the first playthrough in either mode. The remaining 11 manuscripts are only available in Hard Mode, once the game is completed. The ones available in Hard Mode are gained by things like destroying Scorpion Sentinal, or Huntsman. You certainly want some, if not all of these manuscripts to gain the upper hand in the secret bosses.

Each weapon comes with its own weapon ability that can be used as long as the weapon is equipped. However, these weapon abilities can be learned permanently if you max out their proficiency. To earn proficiency, you must use the skill in battle. Each use will grant 10% to the proficiency bar. Fulfill the Proficiency Bonus Each weapon also has a proficiency bonus that, when fulfilled, gives a larger 30% boost to proficiency. Take advantage of these to quickly learn each weapon ability!