Can equipment be activated twice?
No,  That symbol is spend 'any' element once.

page 24 of rules here states


  This multi-colored circle represents any single uses of the six element


This means you can not spend multiple elements to boost the attack.

Note the card does not have the 'refresh item symbol' or 'consumed' symbol  see page 8 of rules.


  if a card depicts neither of these symbols there are no restrictions on the number of times if can be used during a scenario other that was it written in the text of the card


As the card has the symbol to use just one element that is all you can use.

Its also worth looking at this BBG thread on the difference between 'single attack' and 'attack action'.  The item above can only be used on single attacks.  Not on those with an Area Of Effect of targeting more than one enemy in other ways.