If I choose my Irelia fervent starting with 4 might with a spell and then use Irelia's legend ability to ready her, does she get +1 from Irelia's legend choosing her?
No, she does not get the +1 Might bonus for being "chosen" by the Legend ability, but she does get the +1 Might bonus for being "readied."
According to the rules and FAQs for these cards:
- The Legend ability does not "choose" the unit: The Legend ability (Blade Dancer) readies a unit, but it does not count as "choosing" or "targeting" that unit. Therefore, it does not trigger the +1 Might bonus from Irelia, Fervent's ability that triggers when she is chosen.
- She still gets the bonus for being "readied": Irelia, Fervent's ability states: "When you choose or ready me, give me +1 Might this turn." Because the Legend ability successfully readies her, she triggers the "ready" portion of her ability and gains +1 Might.
In summary: You do not get the bonus for "choosing," but you do get the bonus for "readying," resulting in a total of +1 Might from the Legend ability's effect.