Any way to move two symmetrical edges / vertices / faces in opposite directions? I know of the mirror modifier, but say i just want to quickly select a pair (or multiple pairs) of symmetrical vertices / edges / faces of a model. A sword crossguard for example.  

Is there anyway i can just simply select two edges / faces / vertices and transform them in opposite directions instead of in the same direction? (So that i can quickly and easily tweak a model without having to apply a mirror modifier)
If your model is aligned with one of the axes, you can scale your components (edges / verts / faces) along that axis if your pivot point is set to median point (default).