Realistically, pure gold is far too soft to use in tools and weapons (Mohs hardness of 2.5: it can't even scratch an aluminum can), is too nonreactive to chemically convert into anything useful (nothing short of concentrated nitrohydrochloric acid will dissolve it), and gold weakens any alloy to which it's added. That's why no culture on Earth has ever made weapons out of gold. Though kings have loved to hoard gold, it was steel, not gold, that defined history.
You can make weapons out of silver, which is almost as malleable as gold, so why not have gold weapons? History or no, this is DF we're talking about.
You
can, yes, but historically nobody ever did this except for ornamental or ceremonial purposes. Silver is no harder than gold, and is just as unsuitable as a weapon. The value of these metals
as currency partially stems from the fact that they have, until recently, served no industrial purpose. These days they're both used in consumer electronics, though I really don't understand why gold is. Copper is a better conductor than gold, and infinitely cheaper. The reason, really, is that gold electronics are a Veblen good. They're luxury items and owning them is perceived as being a status symbol, despite their inferior performance to cheaper alternatives.
But I digress.
On the flipside, a steel-plated gold hammer with a steel or wooden handle would be very powerful. Ever seen a baseball bat cored with lead? So long as it doesn't break, it will hit a ball ridiculously far.
A lead core bat works better than either a lead bat or a wood bat because it's heavier than the wood bat and more elastic than the lead bat. This relationship doesn't work with steel and gold, because gold is actually
much less elastic than steel. Your hammer would be both heavier and less effective than a pure steel hammer.