His eyes gained sparkle,his mind, which was adequate if not brilliantly equipped, began to move more adventurously

Explanation

The word "adequate" suggests sufficiency but not excellence. It seems contradictory when used alongside "brilliantly equipped." To maintain consistency, the adjective "competent" is more suitable. The corrected sentence is: His eyes gained sparkle, his mind, which was competent if not brilliantly equipped, began to move more adventurously.