Yes, it is a weapon.and then proceed to cite the Ohio state constitution:
§ 1.01 Inalienable Rights (1851)
All men are, by nature, free and independent, and have certain inalienable rights, among which are those of enjoying and defending life and liberty, acquiring, possessing, and protecting property, and seeking and obtaining happiness and safety.§ 1.04 Bearing arms; standing armies; military powers (1851)
The people have the right to bear arms for their defense and security; but standing armies, in time of peace, are dangerous to liberty, and shall not be kept up; and the military shall be in strict subordination to the civil power.
Then I'd look into the laws against malicious prosecution and civil rights violations and go on the offensive. :D
Also the illegal search under the 4th means the evidence (knife) is inadmissible.