What is the test for determining whether a weapon is a deadly weapon?

other grounds in People v. Diaz (2015) 60 Cal.4th 1176, 1189-1190.) We presume the existence of every fact the trier of fact reasonably could deduce from the evidence that supports the judgment. (People v. Kraft (2000) 23 Cal.4th 978, 1053.) We will not substitute our evaluation of a witness's credibility for that of the trier of fact. (People v. Koontz (2002) 27 Cal.4th 1041, 1078.)

Although section 245 does not define the term deadly weapon, case law has defined the term as " 'any object, instrument, or weapon which is used in such a manner as to be capable of producing and likely to produce, death or great bodily injury.' [Citation.] Some few objects, such as dirks and blackjacks, have been held to be deadly weapons as a matter of law; the ordinary use for which they are designed establishes their character as such. [Citation.] Other objects, while not deadly per se, may be used, under certain circumstances, in a manner likely to produce death or great bodily injury. In determining whether an object not inherently deadly or dangerous is used as such, the trier of fact may consider the nature of the object, the manner in which it is used, and all other facts relevant to the issue." (People v. Aguilar (1997) 16 Cal.4th 1023, 1028-1029.)