[Magic Item] Wind Razor

[TyGuy]

What rarity would you put this item as?
Do you think making it finesse is fitting?
Are there any grammatical or technical clarifications needed?
Add a +1 or leave it as is?
Thank you

The description is left open, but this sword is intended to be a katana (reskinned longsword)

Wind Razor
Weapon (longsword), ___ (requires attunement)
This sword has a blade with swirling striations. In addition to melee weapon attacks, you can use the sword to make a ranged weapon attack up to 30 feet. This special ranged attack uses your melee weapon ability modifier and deals slashing damage.
The sword has 7 charges for the following properties. It regains 1d6 + 1 expended charges daily at dawn. If you expend the last charge, roll a d20. On a 1, the sword pulses with a gust of air, loses its properties and becomes a nonmagical longsword.
Gust. You can use a bonus action to expend 1 of the sword's charges to gain the effect of the gust of wind spell (no concentration required). The effect lasts until the start of your next turn.
Ward. You can use a bonus action to expend 1 of the sword's charges to gain the effect of the warding wind spell (no concentration required). The effect lasts until the start of your next turn.
When you attack a creature with this magical weapon and roll a 20 on the attack roll, you may create the effect of Gust or Ward without expending 1 of the sword's charges, no action or bonus action required.

[TyGuy]

Shoot, I forgot to specify a DC for the gust feature. Does DC 16 sound appropriate? I guess that depends on the rarity/power level...

[Amechra]

I feel like this could be a Rare item? I'm not entirely sure, but that just feels right to me.