The Indus Dictionary Project
This is a pictograph of a knife and its sharpening tool. The symbol is equivalent to the Chinese character dāo 刂. It is the verb to cut.
Mohenjo-daro: Seal: M-307 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 76: Collections in India: Suomalainen Tiedeakatemia.
The shape of the symbol resembles a sickle. The technology for such tools is very old. A 7,000 year old boxwood sickle with a curved end for catching the stalks was found at La Draga¹.
The Nepalese khukuri is a good example of the practice of a knife being carried with its sharpening tool.
Indus Script Sign Number 2065: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.
1. La Draga (Banyoles, Catalonia) an Early Neolithic Lakeside Village in Mediterranean Europe: Figure 18, p.28: Catalan Historical Review, 1, 2008: http://revistes.iec.cat/index.php/CHR/article/viewFile/40576/40475: Accessed: 15 November 2017.