This episode establishes the genetic modifications used by Judge to turn his children into emotionless weapons, which is why Sanji (the only one who "failed" to change) was so heavily targeted.
If you are catching up or rewatching, Episode 803 falls within a major sequence of the : One Piece Episode 803
804 ("To the East Blue! Sanji's Resolute Departure") This episode establishes the genetic modifications used by