In Mahdevan's sign number 308, the adjective armed is surrounded by four points of darkness. Each point of darkness signifies that something is false. Hence, the image is false for each
direction, in other words, it is never true. Thus, this is an ideograph for never armed.
Sample Text Reference:
Kalibangan: Seal: K-15 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 301: Collections in India: Suomalainen Tiedeakatemia.
There is only one extant example of this Indus sign.
Indus Script Sign Number 308: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.