Glancing means striking at an angle rather than straight on. The blow slides off instead of landing.
A glancing blow is the standard phrase, and it usually means the damage was far less than it might have been, which is why the word appears in accounts of accidents and near misses. Tanks are built with sloped armour to encourage exactly this. There is a separate sense from the verb glance, since a glancing look is a brief one, and in cricket a glance is a deliberate deflection.
1adjectiveglancingHitting at an angle rather than directly.
“The car caught him a glancing blow and drove on.”