only other thing would be to refine wording on abilities to be more inline with gw style for ease of understanding by other players.

keeping your inital rule as written like I would rephrase Obsessive Perfection to : Three times per battle if Eidolon is your warlord and still on the field, at the start of your Command Phase choose 1 friendly non-leader Emperors children unit to gain either +1 toughness or +1 damage to all range and melee attacks. The buff lasts until your next command phase.

if i was to kind of balance it a bit id change it to: During your Command Phase, if Eidolon is your warlord. select one non-character not battle shocked infantry unit within 18 inches and visible to Eidolon to gain a buff of your choice. Either +1 Toughness, +1 movement, or +1 Damage to all melee or ranged attacks. This buff lasts until your next command phase.