Hand concealment

If the attacker is carrying a weapon, the bearing hand may
be hidden, either in his pocket or behind his back. If one -or
both -of his hands is concealed, beware. Some attackers do
not hide the hands, rather they turn the palm or palms away
from the chosen victim on approach to conceal a weapon, or
keep the offending hand close to their leg to conceal the
same. Other attackers will keep their hands on full display,
extracting a weapon from its hiding place as they approach,
or immediately after asking an engaging question.
My friend was killed in just such a way.