Works on New Blob

code/game/objects/weapons.dm

@@ -2,6 +2,7 @@
 	name = "weapon"
 	icon = 'icons/obj/weapons.dmi'
 	hitsound = "swing_hit"
+	var/cleaving = FALSE // Used to avoid infinite cleaving.
 
 /obj/item/weapon/Bump(mob/M as mob)
 	spawn(0)
@@ -12,4 +13,28 @@
 	item_icons = list(
 			slot_l_hand_str = 'icons/mob/items/lefthand_melee.dmi',
 			slot_r_hand_str = 'icons/mob/items/righthand_melee.dmi',
-			)
+			)
+
+// Attacks mobs (atm only simple ones due to friendly fire issues) that are adjacent to the target and user.
+/obj/item/weapon/proc/cleave(var/mob/living/user, var/mob/living/target)
+	if(cleaving)
+		return // We're busy.
+	cleaving = TRUE
+	var/hit_mobs = 0
+	for(var/mob/living/simple_animal/SA in orange(get_turf(target), 1))
+		if(SA.stat == DEAD) // Don't beat a dead horse.
+			continue
+		if(SA == user) // Don't hit ourselves.  Simple mobs shouldn't be able to do this but that might change later to be able to hit all mob/living-s.
+			continue
+		if(SA == target) // We (presumably) already hit the target before cleave() was called.  orange() should prevent this but just to be safe...
+			continue
+		if(user.faction == SA.faction) // Avoid friendly fire.
+			continue
+		if(!SA.Adjacent(user) || !SA.Adjacent(target)) // Cleaving only hits mobs near the target mob and user.
+			continue
+		if(resolve_attackby(SA, user)) // Hit them with the weapon.  This won't cause recursive cleaving due to the cleaving variable being set to true.
+			hit_mobs++
+
+	if(hit_mobs)
+		to_chat(user, "<span class='danger'>You used \the [src] to attack [hit_mobs] other thing\s!<span>")
+	cleaving = FALSE // We're done now.