I've had to resort to my Latin dictionary and the following site - italatin.com/multilingual.html (website no longer exists) - which offers online translation of Latin phrases as well as other languages.
The banner referred to appears in the painting, 'The Knight's Dream' by Antonio de Pereda (17th century Spanish artist), which is apparently all about symbols of vanity.
On this site the picture can be enlarged and it can then be seen that there is a bow and arrow in the middle of the banner. Given this extra clue, my stab at a translation is something like:
"Eternally it stings, swiftly it flies and it kills."