Hypereutactic blade properly slows you down again, adds set_slowdown() and hooks vv_edit_var for it (#11553)

* ok

* Update items.dm

code/game/objects/items.dm

@@ -855,4 +855,19 @@ GLOBAL_VAR_INIT(rpg_loot_items, FALSE)
 	return
 
 /obj/item/proc/unembedded()
-	return
+	return
+
+/**
+  * Sets our slowdown and updates equipment slowdown of any mob we're equipped on.
+  */
+/obj/item/proc/set_slowdown(new_slowdown)
+	slowdown = new_slowdown
+	if(CHECK_BITFIELD(item_flags, IN_INVENTORY))
+		var/mob/living/L = loc
+		if(istype(L))
+			L.update_equipment_speed_mods()
+
+/obj/item/vv_edit_var(var_name, var_value)
+	. = ..()
+	if(var_name == NAMEOF(src, slowdown))
+		set_slowdown(var_value)			//don't care if it's a duplicate edit as slowdown'll be set, do it anyways to force normal behavior.

code/game/objects/items/twohanded.dm

@@ -58,7 +58,7 @@
 	var/obj/item/twohanded/offhand/O = user.get_inactive_held_item()
 	if(O && istype(O))
 		O.unwield()
-	slowdown -= slowdown_wielded
+	set_slowdown(slowdown - slowdown_wielded)
 
 /obj/item/twohanded/proc/wield(mob/living/carbon/user)
 	if(wielded)
@@ -88,7 +88,7 @@
 	O.desc = "Your second grip on [src]."
 	O.wielded = TRUE
 	user.put_in_inactive_hand(O)
-	slowdown += slowdown_wielded
+	set_slowdown(slowdown + slowdown_wielded)
 
 /obj/item/twohanded/dropped(mob/user)
 	. = ..()