Both Uses

formidable
in
June Recital
(Auto-generated)

So punctual and so formidable was Miss Eckhart that all the little girls passed, one going and one coming, through the beaded curtains mincing like strangers.†
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formidable = intimidating or impressive
Cassie saw that Miss Eckhart, who might once have been formidable in particular to any Mr. Voights, was helpless toward him and his antics—as helpless as Miss Snowdie MacLain would have been, helpless as Miss Snowdie was, toward her own little twin sons—all since she had begun giving in to Virgie Rainey.†

Definitions:

(1) (formidable)
intimidating or impressive -- arousing fear or admiration due to impressiveness or challenge
(2) (meaning too rare to warrant focus)