Having your fellow soldiers die next to you on the battlefield is already pretty traumatic, but at least it's not too hard to convince yourself they're at peace now, and often to "help them along their way" by burying them or having some other ceremony to dispose of the body (I've seen quite a few examples in fiction where one side asks or both sides agree to be allowed to bury their dead, which is a whole lot less practical here).
Now imagine they were to instead be frozen in place while screaming in pain. Are they dead or are they somehow still alive in there, forced to feel that pain and unable to move as long as the statue stands? If they're still alive, is there a way to reverse the "goldification"? Also, imagine the conflicts if one person thinks their thoughts are frozen and they can be brought back somehow, but another thinks they are in a constant state of unbearable pain and leaving them is just prolonging their suffering.
What might be even worse would be having to go back to the battlefield tomorrow and seeing them exactly how they died and unable to do anything about it.
Not only that, but the battlefield might still be scattered with the dead of the last army who tried to attack you.
Additionally, any given soldier getting hit on the battlefield could run around screaming, crying and begging while they slowly turn to gold.
This could very well destroy the morale of any enemies you might have.
If you turn anything into gold with one touch, that would likely change the battle to focus more on avoiding getting hit.
Soldiers would prefer light or even no armour.
The enemy might focus more on sneaky tactics instead of facing you on an open battlefield.
A few arrows would destroy any tight formation (since it would be kind of difficult to hold a formation around some giant blocks of gold), so the enemy would be more thinly spread (either initially or eventually).
Any sort of constructs (catapult, etc.) would get disabled in one touch, so those would be virtually useless.
Some of those things might only be good for you if you know how to take advantage of it (assuming the enemy is at least somewhat well-prepared).
Although it might create more havoc, confusion and demotivation to mix Midas and regular weapons - focus the Midas weapons on what regular weapons are typically weak against.
Would the weapon turn liquid (e.g. water) into gold? If yes:
Take some enemies charging through ankle-high water.
Add one arrow.
Get a bunch of enemies who are stuck in place.
Although this would be more of a one-off trap.
Or launch a giant ball of something very light over your enemies - shoot an arrow at it while it's in mid-air to turn it into a giant ball of death.