Found this on PWC's home page:
What about knives (and other bladed weapons)?
Section 18.2-308 of the State Code, and Section 31-1 of the County Code, prohibit people from carrying concealed dirks, bowie knives, switchblade knives, razors, machetes, ballistic knives (knives with detachable blades that are propelled by a spring-operated mechanism), and a number of other weapons that are not firearms. It is a Class 1 misdemeanor to do so, and such weapon shall be forfeited to the County and may be seized by a police officer as forfeited.
Nothing about blade length or OC of the above items.