Actually I would replace willpower with toughness for the Scum, but in DH scum payers heavy for toughness…
My sugestions for starting aptitudes on Dark Heresy careers:
Adept non-psyker: Knowledge, Social, Intelligence, Perception, Willpower, Fellowship, Agility
Adept psyker: Knowledge, Psyker, Intelligence, Perception, Willpower, Agility
Adepta Sororitas: Offence, Defence, Ballistic Skill, Weapon Skill, Perception, Willpower, Toughness
(if using blood of matyrs there is a lot of varity on this though)
Arbitrator: Defence, Leadership, Ballistic Skill, Toughness, Intelligence, Perception, Fellowship
Assassin: Finesse, Fieldcraft, Weapon Skill, Ballistic Skill, Agility, Perception, Intelligence
Scum: Fieldcraft, Social, Ballistic Skill, Agility, Fellowship, Perception, Toughness
Please notice that all characters has access to the general aptitude.
Also a character can maximum get access to 2 of the non-characteristics aptitudes: Offence, Finesse, Defence, Psyker, Tech, Knowledge, Leadership, Fieldcraft and Social.
You can even see that if you get two of the same aptitudes from character creation, you must replace it with a characteristic aptitude, not one of those above (page 64 at the bottom):
"If, during creation, a character gains the same Aptitude
from different sources, he does not gain it twice. He may
instead choose an Aptitude that he does not already have and
that shares a name with a Characteristic. He gains the chosen
This should be kept in mind when converting Dark Heresy careers to Only War specialties.
Ratling has 3 non-Characteristic aptitudes: Fieldcraft, Finesse, Social.
Iron within, Iron without!
"it wouldn't be 40k if no skulls were involved"
Some how I missed that, all the others only have 2.
The easiest way to convert for both DH and RT I found was to just look at the Stat Increase costs and give them the Aptitudes needed to match those costs. So if the career has a cheep Str increase it would have Strength and Offence aptitudes. This works out to a few oddballs in RT which is the system my group is converting over to OW's rules set but all in all it seems balanced enough for RT so far.