Meanings

to become less capable

skilled

to improve one's skill

to exercise one's talent

brachial muscle

big arm

humerus

wristbone

upper arm

champion of children's sumo

children's sumo

strong arm

diplomatic finesse

skill at administration

naughty boy

group (gang) of naughty (mischievous) boys

resorting (coming) to fisticuffs

to put all one's skill (into doing something)

to be itching to put one's skills to use

one arm