I was arrested while in Las Vegas for Dom battery which I am given to understand will be reduced to simple battery or even dismissed by plea bargain ( I simply grabbed my wife to turn her around while she was walking away from me during an argument, there was no intent to cause injury and no injury was caused but the security in the hotel made themselves busy with it and called the police).
If it is reduced or dismissed it does not constitute moral turpitude and as such do I need to declare it on a new ESTA visa application ? And if not will it flag up anything in any case, I am assuming I will not be put on any kind of watch list so homeland security won't pick it up on receiving the new ESTA application. Do homeland security make check for this kind of thing on their own US criminal database ?

I don't know what Nevada means by "DOM", but I believe DOM Battery (like any battery) would be classified as a crime involving moral turpitude. Grabbing another person against her will, whether harm was caused or intended, is considered immoral, and thus is a "moral turpitude" crime.

Oh. "Domestic" Battery. Never mind.

It will still be domestic battery even if reduced. It appears you have no remorse for this crime, which even makes it worst, and want to blame others for reporting it.

You have no right to grab anyone, even in an argument

Also, see this: https://en.wikipedia.org/wiki/Moral_turpitude#Visa_Waiver_Program

Interestingly, the chart found there indicates that

Assault (https://en.wikipedia.org/wiki/Assault) (simple) (any assault, which does not require an evil intent or depraved motive, although it may involve the use of a weapon, which is neither dangerous nor deadly)

is not a crime involving moral turpitude for the Visa Waiver Program (ESTA). They (presumably the Department of State) are wrong, in my opinion, but they get to make the rules.

As the government will view things as they will, unless you get it completely dismissed (as in no charges), I would think its best to declare it and explain.