The Heroes' Book, page 9, says:
A hero can drop one of their objects in their area as a free action (without assigning gems).
That wording places no time limit on that (e.g. it does not say "one item per turn"), which leads me to suspect that it should read "can drop an item" (or even "can drop any item").
Can someone fluent in French confirm the wording of this rule in the FR manual?
My current interpretation is that a hero may drop any number of items at any time during the heroes' turn. Justification: if a hero has time enough to reload and fire a Crossbow 4 times in his turn, he can also drop more than one item per turn.
Sidebar: players who want to add more detail could decide that wielding or removing a suit of Armor requires a Manipulation action, whereas dropping a weapon or other small item is free. (i'm not one of those players, but maybe you are.)