Hidden Blade

When hidden, this melee weapon can only be
detected by a relevant check of 20 or higher,
and it cannot be removed without surgery. The
blade can be extended or retracted as a bonus
action, and while it is extended you cannot use
the hand of that arm for anything else. The
blade is three feet long when extended, deals
1d8 points of slashing damage, and is a Finesse
weapon.