She has a masculine face, and that would give her assurance in her disguise.

After presenting a theorem (with, say, a highly non-trivial proof), one can sometimes give some assurance that the theorem really holds, by proving a toy version of the theorem.

Shareholders were not given the assurances they sought about reasonable compensation.

In those talks he was not given the assurances he wanted.

The organisers gave an assurance that the insects did not carry malaria.