A. DoraSceptre's origin is much demonic compared to Magic Wand which clearly wield equally powerful yet less demonic evil magic: Witch Bandora got her powers from the pact with Dai Satan in stark contrast of Rita who raised in a family of extraterrestrial spellacters excel in various evil magics accumulated from their homeland and perhaps beyond. One of their notable differences is the mechanic of the spell to enlarge a monster: Whereas Rita's Magic Wand utilizes both magic in the staff and a planet's geothermal energies (the process opens a giant chasm near the staff from which said energy bombards the monster recipient, remember?), Bandora's DoraSceptre instead harnesses demonic power of subterranean evil spirits to do the same feat as shown in this incantation of hers:
|“||O spirits that dwell in the depths of the earth, bestow your evil power upon (monster name)!||„|
B. Related to point above, the power of DoraSceptre, along with contract with Dai Satan which allowed its creation, will be nullified and gone should the wielder shed a tear: When Witch Bandora cries over her son's second death, her magic inevitably lost and subsequently rendered the staff useless. Magic Wand on the other hand, owing to its alien origin and its wielder Rita Repulsa's magical heritage, surely lacked such weakness and may still retaining its evil magic (though as Mystic Mother, Rita stored away her Magic Wand to move on from her villainous past).
Hope this helps.