How does the Slashing Grace feat interact with the Swashbuckler Finesse ability?

Question

The posts I have read indicate that it is possible to take the Slashing Grace feat as a Swashbuckler in order to get DEX to damage with a slashing weapon.

As much as I like the idea I see the following problem. The Slashing Grace feat lists as prerequisite weapon finesse with the weapon to be used, in this case a slashing weapon. But the Swashbuckler finesse is only valid for piercing weapons. Therefore, strictly speaking, Slashing Grace could never be applied to a Swashbuckler with a slashing weapon.

On the other hand, the description of the Slashing Grace feat explicitly refers to the Swashbuckler class and states that "...you can treat it as a one-handed piercing melee weapon".

So, how do these two interact, what is the intention of the RAW rules?

Answer 1

They combine just fine.

From Swashbuckler's Finesse (emphasis mine):

At 1st level, a swashbuckler gains the benefits of the Weapon Finesse feat with light or one-handed piercing melee weapons, and... This ability counts as having the Weapon Finesse feat for purposes of meeting feat prerequisites.

Completely unrelated to what kind of weapons you happen to be wielding at any given time, Swashbuckler's Finesse lets you count as having Weapon Finesse if you ever want to take a feat that requires Weapon Finesse (such as Slashing Grace).

From Slashing Grace (emphasis mine):

Choose one kind of light or 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), ...

When you wield your chosen kind of weapon, Slashing Grace makes it count as a one-handed piercing weapon for any class abilities that are limited to one-handed piercing weapons. Swashbuckler's Finesse is limited to one-handed piercing weapons, therefore Slashing Grace will make your chosen weapon type qualify for the benefits of Swashbuckler's Finesse (as well as some other swashbuckler abilities with a similar restriction).