If you don’t think a golf club is a deadly weapon, then it is you who has lost all credibility. A gun is not a magic shield. A fist can be a deadly weapon, depending on the circumstances. Learn the LEGAL definition of a deadly weapon, rather than the hollyweirdo version of what is a deadly weapon.
Well then, a quarter-cup of water can be a deadly weapon too following that absurd logic.
First and foremost to be a “deadly weapon” something must BE a weapon, it IS NOT SUFFICIENT for something to be used AS a weapon; it must be DESIGNED as a weapon.
Only then can you move on to the qualifier of ‘deadly’; working with the qualifier first as “something that COULD kill” and then expanding it to include all things which might kill which also might be used as a weapon leaves you with a truly absurd set for “deadly weapon.” {A blue whale could be deadly if dropped on someone, if dropped from a bomber as a bomb would would make it a weapon then it must be in the set... truly nonsensical.}