How do the following abilities interact:
You treat any unarmed attack you make while wearing
heavy or powered armor as being made with a battleglove
(see page 187) with an item level equal to or lower than your
soldier level, and you calculate damage for these attacks as
if you had the melee striker gear boost (see page 112). If you
have the melee striker gear boost, you gain a +2 bonus to
damage rolls with your unarmed attacks when using this
ability. These unarmed attacks don’t benefit from other
abilities that apply specifically to unarmed attacks (such as
the Improved Unarmed Strike feat).
Vesk are always considered armed. They can
deal 1d3 lethal damage with unarmed strikes
and the attack doesn’t count as archaic. Vesk
gain a unique weapon specialization with their
natural weapons at 3rd level, allowing them to
add 1–1/2 × their character level to their damage
rolls for their natural weapons (instead of just
adding their character level, as usual).
Since natural weapons lists what the vesk can do with unarmed strikes, instead of referring to it as a different attack, I'm fairly certain that, RAW, the 2 abilities still cannot be combined at all.
I suppose the difference is pedantry in the wording.
For me I read the bit in hammer fist (These unarmed attacks don’t benefit from other abilities that apply specifically to unarmed attacks (such as the Improved Unarmed Strike feat)) as meaning that something like weapon focus: unarmed strike would not work.
However, something that applied to something else, that was used to make an unarmed strike would work.
So the chain is:
ability:unarmed strike:does not combine with hammer fist
ability:natural weapon:used to make unarmed strike:Ability is not specific to unarmed strike:ability combines