Jack takes a moment to absorb that assessment, and decides it's a pretty fair one. Spike's natural speed and strength may be a little muted by the Dome, but he's still got plenty on his side, especially with those fangs just ready to bite.
He grins and lifts the sword ready to strike, only Spike gets there first with his kick, which takes him by surprise enough that Spike's foot does catch his ankle, making him stagger though not actually fall. He stumbles back, laughing breathlessly, and comes in with his sword, aiming more to scratch than stab, because dream or not he doesn't want to really hurt Spike.
((OOC: Oh, absolutely. Jack is hardly the same size, shape or weight as a petite girl, anyway! *g*))