Monster attacking directly considered as "battled"?
Yes, the effect of Michion will activate; direct attacks are included in what are considered "battles".

From Yu-Gi-Oh! TCG Official Rulebook ver9.1 p48


  When a card requires a
  monster to have “battled” (past tense), the attack had to have reached the
  damage calculation portion of the Damage Step in order for the monster to
  have “battled”. If the attack stops before damage calculation, the monster
  did not “battle”.


So, provided Michion's attack reached damage calculation without being interrupted, the effect to halve the opponent's LP will activate at the end of the Battle Phase.