Sarish is Known to His Chosen, ARPG, pg. 222 wrote:
You may now use Arcanum (Sorcery) untrained with
a bonus equal to your Bloodrank. You have also instinctively
learned how to cast a single spell. You learn a single spell
from the Wards or Blood Traditions. If you possess Arcanum
(Sorcery) as a Primary skill, you instead gain a +1 bonus to
all Arcanum (Sorcery) Action Skill Rolls.
1) You gain a spell which MUST come from either the Wards of Blood Tradition. This spell is gained as if you used Learn Spell (ta).
1) If you are not trained in Arcanum (Sorcery), you are able to use the skill using your bloodrank instead to cast the spell that you have gained through your bloodline power.
2) If you ARE trained in Arcanum (Sorcery), then you must use Arcanum (Sorcery) to cast the spell gained through your bloodline power, and you gain a +1 bonus (not +1 rank) to all Arcanum Action Skill Rolls, similar to Prodigy (Sorcerer-Priest of Sarish) (ta).
For Learn Spell:
Learn Spell, ARPG, pg. 200 wrote:
Choose a spell, which must be of a Tier equal to
yours or below, from a Tradition you already know.