Active modern compounds: 挑衅 (to provoke / pick a fight - extremely common in news and diplomatic language), 寻衅滋事 (a specific criminal-code charge: 'picking quarrels and stirring up trouble'), 衅端 (cause of strife / opening for trouble). The original 'blood-sacrifice' sense is now purely classical.
history
The earliest sense, preserved in 《左传》 and 《孟子》, was a ritual: when a new bell, drum, or chariot was completed, sacrificial blood was smeared into its cracks to 'seal' it - 衅钟 (consecrating a bell with blood). From 'crack / seam in a vessel' the meaning extended to 'a crack / flaw in relations' = grounds for dispute, the modern sense.
Components
ideograph
衅xìn
quarrel; ritual blood-anointing
Modern simplified shape - heavily reduced from the traditional 釁 which showed 爨 (the stove / cooking element) over 酉 (wine-jar) plus 分 - together: sacrificial wine being poured and split apart on a vessel's seams. The simplified form keeps only a faint silhouette of that ritual scene. Indexed under Kangxi #143 血 (blood) by tradition; the radical isn't visibly present in the modern simplified glyph.
Filed under radical 血 (xuè, #143) by convention. 血 is not a separate component in 衅, so no strokes are highlighted.
