Green’s Dictionary of Slang

(W.I./S.Afr.) a single-bladed knife with a pattern of three stars on the handle.

1974		K.M.C. Motsisi in Drum (Johannesburg) 22 Mar. 56: Kid Nyaks is in the habit of assaulting non-voters with this ‘ou kappie’ he always wears in his buttock pocket. [Ibid.] 8 July 58: He tells me that he must [...] raise money to pay his creditors one of whom promises to ventilate his body with a ‘ou kappie’ if he does not pay him [DSAE].
1978		D. Marechera House of Hunger (2013) [ebook] I slid my hand into my coat and casually brought out an evil-looking Okapi [...] Knives were not that strange to me.
1980		M. Thelwell Harder They Come 199: They flashed their okapis, the ubiquitous, cheap German-made clasp knives known in the press as ratchet knives, the weapon of choice of the gulleys and slums.
1990		New African 25 June 10: What happened to the proud, energetic cop who would stop you in the street, search you and arrest you for just an okapi (knife) should it be found in your possession? [DSAE].
2008		A. Lovejoy ‘The Smell of Tears’ at www.acidalex.com 🌐 2: The razor sharp Okapi in his other pocket.