Need help with Sawtooth Sabre and Weapon Finesse

[AsheItachi]

Got a person playing a Mantis War priest
He wants His weapon Sabre, Sawtoothed (http://www.d20pfsrd.com/equipment---final/weapons/weapon-descriptions/sabre-sawtooth) to fall under weapon finesse (http://www.d20pfsrd.com/feats/combat-feats/weapon-finesse-combat---final) to use with is Slashing Grace (http://www.d20pfsrd.com/feats/combat-feats/slashing-grace-combat)

And Im telling him it doesnt count a light weapon to meet the requirements of weapon finesse
Am I reading all this wrong?

[Elricaltovilla]

There's an item for that, Effortless Lace (http://www.d20pfsrd.com/magic-items/magic-weapons/specific-magic-weapons/effortless-lace).

[Ssalarn]

Got a person playing a Mantis War priest
He wants His weapon Sabre, Sawtoothed (http://www.d20pfsrd.com/equipment---final/weapons/weapon-descriptions/sabre-sawtooth) to fall under weapon finesse (http://www.d20pfsrd.com/feats/combat-feats/weapon-finesse-combat---final) to use with is Slashing Grace (http://www.d20pfsrd.com/feats/combat-feats/slashing-grace-combat)

And Im telling him it doesnt count a light weapon to meet the requirements of weapon finesse
Am I reading all this wrong?

Sawtooth sabre (http://www.d20pfsrd.com/equipment---final/weapons/weapon-descriptions/sabre-sawtooth)
Description: A sawtoothed sabre may be used as a Martial Weapon (in which case it functions as a longsword), but if you have the feat Exotic Weapon Proficiency (sawtoothed sabre), you treat the weapon as if it were a light weapon for the purpose of two-weapon fighting—the sabre remains classified as a one-handed melee weapon for all other purposes.


So it doesn't count as a light weapon for Weapon Finesse, just for two-weapon fighting purposes.

However, it actually does work with Slashing Grace specifically, since Slashing Grace says "Choose one kind of one-handed slashing weapon (such as the longsword). When wielding your chosen weapon one-handed, you can treat it as a one-handed piercing melee weapon for all feats and class abilities that require such a weapon (such as a swashbuckler's or a duelist's precise strike) and you can add your Dexterity modifier instead of your Strength modifier to that weapon's damage. "

The only issue he would have is getting it to qualify for Weapon Finesse, which would typically require a level of Swashbuckler so he can get Swashbuckler Finesse or something similar. The item linked in above would also work.