Related Rule
South Africa
Practice Relating to Rule 70. Weapons of a Nature to Cause Superfluous Injury or Unnecessary Suffering
South Africa’s LOAC Manual (1996) states:
A basic principle of the LOAC is the prevention of unnecessary suffering. The test in relation to a particular weapon is whether the suffering occasioned by its use is needless, superfluous, or grossly disproportionate to the advantage gained.
i.Weapons which are calculated to cause unnecessary suffering are illegal per se. Such weapons include barbed spears, dum-dum bullets, weapons filled with glass and weapons that inflame wounds.
ii. Legal weapons may not be used in a manner which cause unnecessary suffering. 
South Africa, Presentation on the South African Approach to International Humanitarian Law, Appendix A, Chapter 4: International Humanitarian Law (The Law of Armed Conflict), National Defence Force, 1996, § 34(f).
South Africa’s Revised Civic Education Manual (2004) states:
35. The following three principles govern the LOAC:
b. Prevention of Unnecessary Suffering: … It is especially forbidden to employ arms, projectiles or material calculated to cause unnecessary suffering. The two-part test is to determine whether military action:
i. causes unnecessary suffering; or
ii. is calculated to cause unnecessary suffering. 
South Africa, Revised Civic Education Manual, South African National Defence Force, 2004, Chapter 4, § 35; see also § 56(f) (“Prohibitions/Restriction on Certain Types and Use of Weapons”).
South Africa’s ICC Act (2002) reproduces the war crimes listed in the 1998 ICC Statute, including in international armed conflicts:
employing weapons, projectiles and material and methods of warfare which are of a nature to cause superfluous injury or unnecessary suffering … provided that such weapons, projectiles and material and methods of warfare are the subject of a comprehensive prohibition and are included in an annex to the [1998 ICC] Statute by an amendment in accordance with the relevant provisions set out in Articles 121 and 123 of the Statute. 
South Africa, ICC Act, 2002, Schedule 1, Part 3, § (b)(xx).