Boots of lightness are weight-reducing equipment. Although they (or some other weight-reducing item) are required during the Temple of Ikov (quest), they can be obtained and worn by anyone (members-only) at any time, even without starting the quest.
Source: http://runescape.wikia.com/wiki/Boots_of_lightness
Yeah, I got a pair on my skiller (0 QP and non-started)

