Hi Dylan d,
The little pin thing is a bamboo (typically, or traditionally) piece, a little tapered peg, called a mekugi. A person can tap the peg out (longer blades may have two) and can remove the handle (tsuka, pronounced kinda like "ska") to clean the blade, or (especially older swords) to check the signature. The tang (nakago) is allowed to rust or patina naturally, which can make older blades hard to identify (the maker, that is). The mekugi typically enters from the right, if at the front of the handle, so your right hand blocks it from coming out during use, though it should be a fairly tight fit. Hope you don't mind that I answered for you, Bailey!
James
The little pin thing is a bamboo (typically, or traditionally) piece, a little tapered peg, called a mekugi. A person can tap the peg out (longer blades may have two) and can remove the handle (tsuka, pronounced kinda like "ska") to clean the blade, or (especially older swords) to check the signature. The tang (nakago) is allowed to rust or patina naturally, which can make older blades hard to identify (the maker, that is). The mekugi typically enters from the right, if at the front of the handle, so your right hand blocks it from coming out during use, though it should be a fairly tight fit. Hope you don't mind that I answered for you, Bailey!
James