To defeat Commander Honglan in Wuchang Fallen Feathers you need to parry, counter or dodge her attacks and build up the Poise Break meter to be able to use Obliterate. Use Charged Heavy Attacks when you're safely behind her to also trigger Obliterate while using Light Attacks where it's safe to do so.

Fallen Feathers. Five of them are timed debuffs, while two of them are instantly applied upon infliction—but they’re all equally dangerous in the right situation. You should always wear gear that helps protect you against any status effects in the area you’re exploring,