After much waiting I finally got the axe from tortos, then I got a thunderforged one
Now of course I'm going to be replacing my worldbreaker n 2/2 with thunderforged shellsplitter, and as such I upgraded that first this week
but what should I upgrade next, the rest of my gear and leave scimitar n 2/2 as my off hand or upgrade/gem/enchant etc the normal shellsplitter too.
also my guild has killed hc jinrok so i will have a chance of killing that and as such a chance at the heroic weapon next week.
Weapons>trinkets>tier pieces. Legs(jikun) and shoulders(Ironqon) are easiest to get on heroic. Maybe wait with upgrading your other weapon until you kill hc jinrokh again and if it doesn't drop just upgrade it and other gear you're not likely to replace soon.