Use material defines more

code/game/objects/items/weapons/material/knives.dm

@@ -66,7 +66,7 @@
 	sharp = 1
 	edge = 1
 	force_divisor = 0.15 // 9 when wielded with hardness 60 (steel)
-	matter = list(DEFAULT_WALL_MATERIAL = 12000)
+	matter = list(MAT_STEEL = 12000)
 	origin_tech = list(TECH_MATERIAL = 1)
 	attack_verb = list("slashed", "stabbed", "sliced", "torn", "ripped", "diced", "cut")
 	drop_sound = 'sound/items/drop/knife.ogg'

code/game/objects/items/weapons/material/material_armor.dm

@@ -201,7 +201,7 @@ Protectiveness | Armor %
 
 /obj/item/clothing/suit/armor/material
 	name = "armor"
-	default_material = DEFAULT_WALL_MATERIAL
+	default_material = MAT_STEEL
 
 /obj/item/clothing/suit/armor/material/makeshift
 	name = "sheet armor"
@@ -401,7 +401,7 @@ Protectiveness | Armor %
 /obj/item/clothing/head/helmet/material
 	name = "helmet"
 	flags_inv = HIDEEARS|HIDEEYES|BLOCKHAIR
-	default_material = DEFAULT_WALL_MATERIAL
+	default_material = MAT_STEEL
 
 /obj/item/clothing/head/helmet/material/makeshift
 	name = "bucket"

code/game/objects/items/weapons/material/material_weapons.dm

@@ -23,7 +23,7 @@
 	var/force_divisor = 0.5
 	var/thrown_force_divisor = 0.5
 	var/dulled_divisor = 0.5	//Just drops the damage by half
-	var/default_material = DEFAULT_WALL_MATERIAL
+	var/default_material = MAT_STEEL
 	var/datum/material/material
 	var/drops_debris = 1
 

code/game/objects/items/weapons/material/twohanded.dm

@@ -174,7 +174,7 @@
 	force_divisor = 0.3
 	force = 10
 	thrown_force_divisor = 1
-	default_material = "DEFAULT_WALL_MATERIAL"
+	default_material = "MAT_STEEL"
 	fragile = 0
 	sharp = 1
 	edge = 0