Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 79. Weapons Primarily Injuring by Non-Detectable Fragments
The UK Military Manual (1958) prohibits the use of projectiles filled with broken glass. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 110.
The UK LOAC Pamphlet (1981), under the heading “Future Developments”, considers the possibility, thanks to the 1980 Convention on Certain Conventional Weapons, of “a ban on weapons whose main purpose is to produce fragments that cannot be detected by X-ray”. 
United Kingdom, The Law of Armed Conflict, D/DAT/13/35/66, Army Code 71130 (Revised 1981), Ministry of Defence, prepared under the Direction of The Chief of the General Staff, 1981, Section 11, p. 40, § 4(c).
The UK LOAC Manual (2004) states in its chapter on weapons:
Fragmentation Weapons
6.11. The general rule prohibiting the infliction of unnecessary suffering or superfluous injury does not preclude the use of hand-grenades and other fragmentation weapons.
6.11.1. The general rule must be taken as banning the use of weapons or projectiles that discharge broken glass, nails, and the like.
6.11.2. The use of “any weapon the primary effect of which is to injure by fragments which in the human body escape detection by X-rays” is prohibited. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, §§ 6.11–6.11.2.