We have two options. First, Putin is bluffing. This is what most people believe (and hope). In this case giving Ukraine more weapons won't hurt anyone. Option two is that he is really planning some offensive action this winter. In this case sending weapons to Ukraine could help in slowing the Russians down. It could also help in decimating their army - if they unmask as a ruthless aggressor, it is in the interest of the whole civilization, not just the EU, to limit their impact.