Okay, big edit. Instead of just us guessing I actually went to Otakon's site, and this is what they have to say about weapons:
Weapons at Otakon
Weapons NOT Permitted
Weapons not permitted at Otakon include, but are not limited to the following:
NO LIVE STEEL at all will be permitted on the premises of the BCC. Live steel is defined as swords, knives, bayonets, and/or other objects made of metal, which can take an edge. This holds true regardless of whether the object is actually sharp. This includes star knives/shurikens. A sheathed sword is still live steel as is any metal armor.
NO GUNS of any kind will be permitted. Examples include, but are not limited to, pellet guns, BB guns, air guns, crossbows, dart guns, blowguns, water guns, or water pistols. Real guns, replicas of real guns, stun guns, and tasers are also prohibited. The ONLY exception to this rule will be prop guns or resin models that are easily identifiable as toys, provided that they possess no moving parts and are clearly marked with a non-removable orange tip.
No "paddles", of any sort, will be allowed at the convention. This includes, but is not limited to Yaoi/Yuri Paddles.
All "airsoft" guns are prohibited, including any gun that has ever been an "airsoft" gun, even if they are no longer operational. This includes all "airsoft" spring, gas, or electrically operated guns.
Nunchaku are not permitted.
Explosives or chemicals of any kind including, but not limited to, smoke powder, sparklers, and fireworks, are not permitted at the con.
Finally, if it is illegal outside in the City of Baltimore and/or State of Maryland, it is illegal inside the BCC.
Illegal weapons will be reported to the appropriate authorities.
Weapons Permitted
Staves, bo sticks, boken, shinai, and wooden swords will be permitted as long as they are handled responsibly and meet all other criteria. For information on wooden paddles see above in the items which are not permitted.
Fake, prop, or made-up weapons (i.e. made of tissue paper, plaster of Paris, cloth) are permitted if they are safe and not dangerous to others around you. (Dangerous conditions include, but are not limited to, wires sticking out, items that trip others, clothes lining someone, etc.)
Prop weapons shall be limited to less than six feet six inches (6'6") in height and less than fifty pounds (50lbs) in weight.
Any metal chains are to be less than three feet (3'). This includes, but is not limited to chain wallets or any non-costume chains as well.
Behavior with Weapons
Misuse of any weapon or prop, such as swinging it in a public area or causing hazards to others, will result in the weapon or prop being deemed unsafe for the convention.
If a weapon or prop is deemed unsafe for the con, we will ask you to remove the weapon or prop from the convention and store it in your private quarters (your home, hotel room, or car).
Any weapon purchased in the Dealer's Room must be boxed and removed from convention property immediately, and should remain boxed and stored in your private quarters. Weapons are not to be taken out of their packaging or wrappings while on BCC property.
All props and weapons brought into the convention may be inspected and approved or rejected by Otakon staff, including those that may have prior approval (other conventions, previous conventions, or pre-convention approval by Otakon staff).
Any item that poses a potential safety hazard is subject to challenge and may need to be removed from the convention. For example, any costume, prop, or accessory which is too wide or bulky to maneuver the halls safely may be disallowed.
In the event your weapon/prop is approved by one staffer, and is contested by another, the head of Spec Ops will make a final ruling. Please note that just because a staffer has not stopped you to check your item, does not mean that the item is allowed.
All decisions made by Otakon and/or the Public Safety Staff of the Baltimore Convention Center are final.