fighters and racial weapon feats.

[Hammerspace]

most races have their racial weapon feats.
level 1: easier access to racial weapons.
level 5: crits
level 13: proficiancy equal to highest proficiacy.

at first I thought that only the level 1 feat might be usefull for fighters.
But then looked more carefully at how fighters work.
at level 5 the fighters picks a weapon type and gets mastery with that one.
And gains the ability to get the crit special from weapons he mastered.

So if I understand the rules correctly and I want to play a fighter that likes to swap weapons there is good value in the level 5 and 13 weapon feats.

If I want to play an elven fighter that specializes in swords, but still likes to use a bow, he can take the level 1 and level 5 feat so he can also crit with the bow.
at level 13 I can replace the level 5 feat with the level 13 feat and become legendary with all my racial weapons.(removing the need for the level 5 feat)

[Castilliano]

Yes.

You could pick a weapon group that contrasts well with your Ancestry weapons to get a good spread of damage types & weapon traits, especially ranged as you've noted w/ the elf example.

I likely wouldn't pick up the crit specialization feat, though that depends on other feats and what specializations.

Technically, you couldn't replace the 5th level feat w/ the 13th level feat. The 5th level feat already gets overridden by mastery in all non-advanced weapons, so you'd be retraining that for a different Ancestry feat of 5th level (or 1st). Whether you take the 13th level feat is completely separate (unless there's an advanced weapon in the set you're using).

[Hammerspace]

Ok retrain the level 5 feat into something usefull while taking the level 13 feat. I am kinda used to 4th edition D&D.

Critting can be a bit random, so you're probably right about there being other usefull racial feats.