Before I given an example of a sample sentence showing both words, let us dissect the meaning of each word first. The synonyms are as follows:
deftly –in a deft manner; quickly and neatly in action
synonyms - skillfully, cleverly, smartly, precisely
Symmetry- exact correspondence on either side of the dividing line, plane, center, or axis.
synonyms balance, proportion, evenness
Sample Simple Sentence:
George has deftly achieved the symmetry of the entire structure.
Hope that helps :)