Now that the quarterback has recovered from his injury, this week the team will be functioning 'at full strength' again. [=the team will have all its players again]
We are negotiating from a 'position of strength'. [=from a strong position; from a position that gives us an advantage]
He didn't mean to knock you down; he just 'doesn't know his own strength'. [=doesn't realize how strong he really is]
(..) The Black Knight has returned, and seeks a match with you. The Black Knight...? None other. ls he pretty tough? He has the strength of ten, and cunning besides. But... ...his sight is weak in his left eye. Stay to his left and you will prevail and win the day. (..)1973 Westworld