Sending 1 card to the Graveyard is a cost. This is not "discarding" so it doesn't trigger "Forced Requisition", and you can pay the cost even if "Goblin of Greed" is in play.
If a monster equipped with "Wicked-Breaking Flamberge – Baou" attacks and destroys "Amazoness Fighter" or "Amazoness Swordswoman", their effects are not negated because they happen during damage calculation, before they are determined to have been destroyed.