Il vous fera un mauvais parti = He will try and pick a quarrel with you so as to ill-use you, to do you harm.
Partie
Il m’a pris à partie = He took me to task; (legally) He summoned me.
[Partie is literally a man who pleads against any one in a lawsuit. Compare:
“Va, je suis ta partie et non pas ton bourreau.”
Corneille, Cid, 839.]
C’était une partie nulle = It was a drawn game.
Pas
Marcher à pas de géant = To put on one’s seven-league boots.
Se tirer d’un mauvais pas = To get out of an awkward fix (scrape).
*Il n’y a que le premier pas qui coûte = In everything the beginning is the most difficult part; The first step downward makes the others easier.