The enlarge/reduce spell states:
[...] If the target is a creature, everything it is wearing and carrying changes size with it. Any item dropped by an affected creature returns to normal size at once [...]
Reduce. [...] The target's weapons also shrink to match its new size. While these weapons are reduced, the target's attacks with them deal 1d4 less damage [...]
If the enlarge/reduce (choosing reduce) spell is cast on you, can you simply pick up a regular-sized weapon to avoid the 1d4 damage reduction? Alternatively, can the creature drop a reduced weapon, and then pick it back, removing the 1d4 damage reduction? In other words, what happens when a creature affected by enlarge/reduce picks up an item?