Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Praestāna, ae, f. [2. praesto], the goddess of excellence, who was worshipped because Romulus had surpassed all others in throwing javelins: Praestana est, ut perhibetis, dicta, quod Quirinus in jaculi missione cunctorum praestiterit viribus, Arn. 4, 128.