Build advice - swashbuckler whirling dervish

Looking for some help with a whirling dervish architype for the swashbuckler.

Race Human
Adopted parentage - (elf-weapon familiarity)
Level 1 feat ancestral weapon mastery - to pick up access to elven thornblade with the plus 2 on confirm crits
also - get weapon focus (elven thornblade) for free w/ancestral weapon mastery as I am already proficient

@ level 4 this will also allow for dex to damage with dervish finesse changes to swashbuckler finesse as the thornblade is both piercing and slashing...
with imp. crit 15-20 at level 5 and damage is 1d6 +1(swashbuckler training) + dex bonus + 5 for precise strike
ok...the question....

Is it better to build out something around bastard sword as an option instead
to get an additional feat back? Would need to burn the feat back on slashing grace (bastard sword) as it is only slashing and not piercing, but this would work with swashbuckler.

crit 17-20 w/lvl 5 being 1d10 +1(training) + dex bonus +5 precise strike

is the crit range increase worth the every hit damage difference between 1d6 and 1d10

thoughts?
thanks!

Adoptive Parentage costs you the human bonus feat, meaning you effectively spend two feats for Weapon Focus and a +2 to attack rolls. Considering the latter is only half a feat, and not a good one, that a terrible trade.

Whirling Dervish needs a high crit range weapon even more than other Swashbucklers, that makes Bastard Sword a bad weapon. With no extra feat investment, a bastard sword would be narrowly ahead of a 1d6 18-20 weapon, but not enough to justify the lower panache recovery, and definitely not enough to spend a feat or (even just a trait) on.

Why not save a lot of trouble and just use a scimitar like the archetype is designed to. Take the trait merciful scimitar to allow you to do non-lethal damage with the scimitar. This allows you to gain panache from dropping a fore below 0 HP by dealing non-lethal damage. this trait only works with the scimitar.

Adoptive Parentage costs you the human bonus feat, meaning you effectively spend two feats for Weapon Focus and a +2 to attack rolls. Considering the latter is only half a feat, and not a good one, that a terrible trade.

Whirling Dervish needs a high crit range weapon even more than other Swashbucklers, that makes Bastard Sword a bad weapon. With no extra feat investment, a bastard sword would be narrowly ahead of a 1d6 18-20 weapon, but not enough to justify the lower panache recovery, and definitely not enough to spend a feat or (even just a trait) on.

Thanks - I was thinking of it more as bonus feat - adoptive....which I agree is a loss....followed by free weapon focus with ancestral weapon mastery which is a wash if you consider your level 1 feat could have been weapon focus in any case -

Your points on the panache recovery with the crits are well-taken I had forgotten that little detail.

thanks for the feedback

If you are going for that archetype, using a scimitar is pretty much superior to all alternatives.

All you need is a trait slot for non lethal damage.