Hi Chris,
the magnets are available in various 'strengths' and dimensions. I am certain that to 'overcome' the scabbard/sheath 'magnetic insulating' (not a technical term, you understand
) properties, a stronger magnet would be required.
As a foot note, a 'column' could also be made for the hilt end ( if the design of the guard, hilt and pommel is not easy to 'fix' that end of the sword) Or alternatively 2 or 3 'columns' with magnets attached to carry the blade so that the hilt is in effect 'free floating'.
Regards David