Phasing is one of the many special abilities an elf may manifest. Phasers have the ability to break down their cells (in a manner similar to light leaping) to walk through solid objects. Some talented Phasers are able to incompletely disassemble themselves, causing them to appear blurred and "smudged." Blur, a member of The Collective, uses this ability to mask his identity - thus his alias. Blur has also demonstrated the ability to sense an object's inner functions by passing an intangible hand through the object. To what level Phasers can sense through this ability is unknown.
“You just walked through a wall."..."Phasers do that sometimes.”