'less of a danger' is correct and can be used in written English.
You can use it when you want to compare two risks and indicate that one of them is less severe than the other. For example, "Running is considered less of a danger to your health than smoking."
Specifically these items assess attitudes regarding commonality (Virtually anyone can become mentally ill); dangerousness (People with mental health problems are far less of a danger than most people suppose); and responsibility (People with mental health problems should not be given any responsibility).
That now looks less of a danger.
Being only one such threat does not make Mr Hussein less of a danger.
Yet eventually the virus may become less of a danger thanks to a phenomenon called herd immunity.
At Flex there are currents and riptides and veritable tsunamis, and monotony is less of a danger than drowning.
And although a weaker currency can push up inflation, this is less of a danger when the euro area's inflation rate is only 1%.
Not only is an "unknown" birth mother unlikely to reclaim her child across oceans (in fact, disruptions of U.S. adoptions are also rare once the adoption is legally finalized), but she can also seem like less of an emotional danger — as if physical distance creates psychological distance.
Another one of the Brics with clear problems is Brazil, though it poses less of an international danger.
Find some area of the concrete jungle that looks enough like a maze but poses less of a challenge (and danger) than the Great Wall of China.
The question of whether Lessing posed a danger is better answered by her books than by her MI5 files.
But it is no less of a mistake to imagine that the dangers of terrorism, proliferation and war will simply vanish if America were now to walk away from all the bad places.
