A blood arcanist selects one bloodline from those available through the sorcerer bloodline class feature. The blood arcanist gains the bloodline arcana and bloodline powers of that bloodline, treating her arcanist level as her sorcerer level. The blood arcanist does not gain the class skill, bonus feats, or bonus spells from her bloodline.
Starting at 9th level, whenever you gain a new level of spells, you automatically replace any psychic bloodline spells that can be undercast with the highest-level version you can cast in your list of spells known. For example, at 9th level, you would replace mind thrust I, id insinuation I, and ego whip I with mind thrust IV, id insinuation III, and ego whip II, respectively, as spells known.
How does these two interact? Initially I figured that since the Arcanist prepares spells, the "spells known" part would leave it with a dead class feature, yet it states in the spell casting part that an Arcanist may know any number of spells - so that one seems to work.
However, the bolded portions is what seems to potentially cause conflict.
As read, it seems as if the Psychic Blood Arcanist has no bloodline spells for the first 8 levels of his career - and starting from there, he automatically replaces any psychic bloodline spells that can be undercast with the highest-level version available in his spells known - no mention made of him actually having access to the spells.
Granted, the word "replace" indicates that this would only happen if you had these spells already available, but it also means to put something back - which this bloodline power does.
Thoughts on this curiosity?
It seem pretty useless since you don't have access to spells which allow undercasting. A Sorcerer with this bloodline would get undercastable spells as bonus bloodline spells, but Blood Arcanists seem to be out of luck.