Which preposition to use with incisiveness

of Occurrences 3%

It aims at comparatively little, but is perfectly successful in its aim, and unsurpassed for the incisiveness of its side strokes, and the courtly ease of a manner that never degenerates into mannerism.

under Occurrences 1%

He viewed his whole life now, in epitome, and much as you may see at night the hackneyed vista from your window leap to incisiveness under the lash of lightning.

Which preposition to use with  incisiveness