Offend
late Middle English: from Old French offendre, from Latin offendere ‘strike against’.
wiktionary
From Middle French offendre, from Latin offendō(“strike, blunder, commit an offense”), from ob-(“against”) + *fendō(“strike”).
etymonline
offend (v.)
early 14c., offenden, "to disobey or sin against (a person, human or divine)," a sense now obsolete, from Old French ofendre "hit, attack, injure; sin against; antagonize, excite to anger" and directly from Latin offendere "to hit, thrust, or strike against," figuratively "to stumble, commit a fault, displease, trespass against, provoke," from assimilated form of ob "in front of against" (see ob-) + -fendere "to strike" (found only in compounds; see defend).
Meaning "to violate (a law), to make a moral false step, to commit a crime" is from late 14c. Meaning "to wound the feelings of, displease, give displeasure to, excite personal annoyance or resentment in" is from late 14c. The literal sense of "to attack, assail" (late 14c.) is obsolete, but it is somewhat preserved in offense and offensive. Related: Offended; offending; offendedness.
