[A] Any object or instrument other than nature’s weapons that is used in wounding or doing serous bodily injury to a person is a deadly weapon if it is likely to produce death or great bodily injury when used in a manner and under the circumstances in which it was used. You are the judges of whether the weapon used by the defendant in this case was a deadly weapon when used in the manner and under the circumstances in which it was used as disclosed by the evidence.

[B] A deadly weapon is one that is likely to produce death or great bodily injury from the manner in which it is used.