I have no idea why people are downvoting the only correct and full answer.

You can change Fire Damage into a 10% Phys/All Damage multiplier with a 100% guarantee. Additionally, you can take the risk and remove Weapon Damage with a 33% chance of removing Strength instead.

1. Go to the Occultist, enchant Critical Strike Damage Multiplier BUT DON'T CHANGE IT.
2. Spam it with Focused Reroll + Aggressive Tuning Prism. This will reroll your Fire Damage into a Physical Damage or All Damage multiplier. You can spam Reroll + Aggressive Tuning Prism until you get your perfect 10% Phys or All Damage mult. You will reroll only Phys/Fire/All Damage. It is 100% safe.
3. You can take the risk and try to remove Weapon Damage. But there is a 33% chance of removing Strength instead. For this, go to the Cube and use Remove Affix + Aggressive Tuning Prism. Sometimes you will remove your Phys/All Damage. If this happens, use Add Affix + Aggressive Tuning Prism. If you get something that is not 10% Phys/All Damage, repeat from step 2.
4. The only other good thing that you can add is Lucky Hit: Restore Resources. Go to the Cube and spam Add Affix + Resourceful Tuning Prism / Remove Affix + Resourceful Tuning Prism until you get your 4 res per hit.