Bug fixes: trial by fire (#4990)

-fixes #4697
-fixes #3913
-fixes #3216
-fixes #1854
-fixes #901
-fixes #1597
-fixes #4469
-fixes #1215
-fixes #3681
-fixes #3567

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

@@ -50,7 +50,7 @@
 	if(iswelder(W) && material.shard_can_repair)
 		var/obj/item/weapon/weldingtool/WT = W
 		if(WT.remove_fuel(0, user))
-			material.place_sheet(loc)
+			material.place_sheet(user.loc)
 			qdel(src)
 			return
 	return ..()

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

@@ -100,6 +100,10 @@
 	else
 		return
 
+	if(!istype(user.get_active_hand(), src))
+		user << "<span class='warning'>You need to be holding the [name] in your active hand.</span>"
+		return
+
 	if(wielded) //Trying to unwield it
 		unwield()
 		user << "<span class='notice'>You are now carrying the [name] with one hand.</span>"
@@ -113,7 +117,7 @@
 
 	else //Trying to wield it
 		if(user.get_inactive_hand())
-			user << "<span class='warning'>You need your other hand to be empty</span>"
+			user << "<span class='warning'>You need your other hand to be empty.</span>"
 			return
 		wield()
 		user << "<span class='notice'>You grab the [base_name] with both hands.</span>"

code/game/objects/items/weapons/trays.dm

@@ -214,9 +214,9 @@
 	return 1
 
 /obj/item/weapon/tray/AltClick(var/mob/user)
+	if (!use_check(user, show_messages = FALSE)) return
 	unload(user)
 
-
 /obj/item/weapon/tray/proc/attempt_load_item(var/obj/item/I, var/mob/user, var/messages = 1)
 	if( I != src && !I.anchored && !istype(I, /obj/item/projectile) )
 		var/match = 0