A careful review of rule 701.3 revealed to me that the equip ability never targets (unless I am mistaken). Therefore, could I equip a Loxodon Warhammer to a creature already equipped with Lightning Greaves? Why or why not?
Equip does target:
702.6a (http://imtgapp.com/forum/index.php?action=imtg;area=rule;number=702.6a): Equip is an activated ability of Equipment cards. "Equip [cost]" means "[Cost]: Attach this permanent to target creature you control. Activate this ability only any time you could cast a sorcery."
Perfect. Now I know.