good tip for metals:
- basic color: black (yes, black)
- high spec, color: grey to white for steel/chrome, others for coloured metals (copper, brass…)
- reflections, at least for polished metals. raytracing is maybe too clean, use animated env-maps instead (coz you can also blur them a bit).
for a good effect, you can also use two materials for the sword: a less specular, darker base material, and a high-spec, highly reflective material for the cutting edge.
the skull is tricky… i also think the halo-trick is your best bet. you might also look if some of the other supported renderers (yafray, aqsis, virtua light etc.) have support for volumetric rendering. if you manage to set up things correctly, you can render this part externally and integrate it in the final shot via compositing.