They do not derive merely from his possession of weapons, but from the way that he wielded those weapons against Americans. Compare and contrast: this dude is **not** accused of wielding weapons against Israel, but merely that he designed weaponry. Colin is therefore correct and you, so sorry, are wrong i.e. the charge sheet only "sticks" if you assume Israeli sovereignty over Gaza.
Jerusalem Gay Pride Parade: Stabber is Yishai Shlissel, the 2005 parade attacker (Haaretz)
from the article: 'Hamas weapons capability increased four-fold over last five years'