Here's something fun I found while checking bulbapidea;

Honedge weighs 4.4 lbs.

Doublade weighs 9.9 lbs.

And Aegislash weighs 116.8 lbs.

Meanwhile; Autotomize reduces weight by 220 lbs in exchange for raising the speed stat by two stages.

Every member of the Honedge evolution line can make themselves weigh less then nothing. There's a reason why I named my character Mithril. Just putting this up here to show that when I said that Mithril made himself weightless, what I meant was that he was weightless [i]at the most[/i].