弑 specifically means killing a superior — a son killing his father, a subject killing his ruler — and is laden with classical Confucian moral horror. 《孟子》: 弑父与君，亦不从也 (one would not follow even an order to kill one's father or ruler). Plain 杀 (kill) lacks this charge.
mistakes
Don't confuse 弑 (shì, kill a superior) with 杀 (shā, kill, general). The 弋 element on the right is part of 弑 — not 戈.
