Weapon Help

[Mandalore108]

So I made the following weapon and I was hoping I could get some feedback on making it balanced:

Greatsword of Force

Damage is related to the characters strength. 10-11 is 0 additional damage. 12-15 = 1d4 force damage. 16-19 = 1d6 force damage. 20 = 1d8 force damage. The inverse is also true as the sword will damage those not strong enough to wield it.

The sword also has 3 charges which can be used as follows:
Ranged attack of 45 feet doing 2x the above force damage + strength modifier. If used at melee range the enemy takes normal damage plus the additional 2x. Additionally, the enemy must make a strength saving throw or be knocked prone or knocked back 10 ft depending on the swing of the user. The user rolls every morning to determine how much is recharged.

[Mandalore108]

Any suggestions/improvements would be appreciated.

[Kane0]

You may want to simplify this a little. How about:

Sword of Force
Rare Weapon (greatsword)
Requires Attunement

This sword functions as a +0 magic greatsword, adding the wielder's STR bonus as additional Force damage on a hit.
This weapon has 3 charges. The wielder can use their action to expend one charge and make a ranged weapon attack using the sword with a range of up to 60 feet. On a hit the target must also succeed a Strength Saving Throw (DC 16) or be knocked prone. The sword then returns to the wielder.
Each dawn the sword regains 1d4-1 expended charges.

[furby076]

Whats the backstory of the sword? Maybe its history will shed some light

Its underwhelming, tbh. Its only good use is the thrown ability, but thats limited to range. I would sell it

[QuintonBeck]

Definitely worth simplifying. I would just say plus 1d6 Force damage regardless of strength. I'd also model the burst/range attack language around the paladin's smite.

"In addition, this sword has three charges. Each charge spent adds an additional 1d6 Force damage on top of the sword's base damage. Expending a charge allows an optional ranged attack (45 ft) forfeiting the Greatsword's physical damage."

EDIT: I disagree it's underwhelming. Three free (as in they don't eat into Action Economy) chances to force a Strength save versus prone on a Greatsword is like Shield Master, but with a Greatsword. (Perhaps the Strength save DC could be set by the wielder's Strength mod to incorporate the PC's stats as the original proposition did) That it deals the nearly un-resistable Force damage as it's extra damage is just gravy. Giving it a ranged attack is just the sign of a kind DM giving a melee character some ranged options.

[stoutstien]

Instead of the usual charge mechanic I like to cause the item the activate using hit die so the item is continually more useful as a level up but is always a con Pro. I'm extremely stingy about magic items expecially any magic item that has a flat +, mostly because I take full advantage of the resistance vulnerability tags that the monster manual under utilize IMO.