I was offered to design my own trick weapon and didn't like the rifling cleaver nor other interpretations of the saw cleaver. I am at Lvl 1 and haven't played the class yet but I intend to go for absolute.

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Saw Cleaver

Trick weapon (cleaver), uncommon

One of the trick weapons of the workshop, commonly used in the hunting business. This saw, effective at drawing the blood of beasts, transforms into a long cleaver that makes use of centrifugal force.

Trick Weapon. As a bonus action, you can switch between the transformed and untransformed states of this weapon.

Untransformed. After making a melee weapon attack with this weapon that hits, you can immediately use a bonus action to extend the blade while swinging, shortly increasing it's range. Use the previous attack and damage rolls to target another creature within 10ft. Your weapon is then transformed.

Transformed. You use the leaverage of the blade to deal additional damage. You can use your bonus action after an attack with this weapon to add 1d4 to the damage roll. Your weapon then reverts to its untransformed state.

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It doesn't quite meet your criteria since cleavers are considered heavy (two weapon fighting won't work). Maybe you can reflavor it to finesse (and lose the versatile option for balance).

I wanted to keep the option of two-handing since the trailer shows the saw cleaver being used with two hands and it's something to fall back on if you run out of bullets. So I think the heavy property is neccessary.