The other difference between the Israelites and the Assyrians was that the Israelites carried the Arc of the Covenant into battle. From the description, a box of a specific type of wood, lined inside and out with gold leaf, it makes a decent example of a "Leyden jar", such as Benjamin Franklin experimented with in the Philadelphia area several thousand years later. Connect the Leyden jar to a metal head on a long wooden pole via a chain, and have that at the forefront of your army. The first soldier in the opposing army to hit or be hit by that metal head gets a real surprise, and if the army has its shields firmly locked for mutual protection against sling bullets and stones, the whole front line draws an "arc" from the Arc.....and then your troops charge them. The descriptions of the "Holy of holies" and the strange lights can be easily explained if the priests are dealing with extremely high voltage electricity and attempting to capture lightning bolts to recharge the Arc.
A Leyden Jar is a form of capacitor - it required an external voltage to charge it. Unless we assume the Israelites had access to batteries or generators as well then it is unlikely it would work. In addition, the chage a primitive Layden jar can hold is quite limited - not enough to incapacitate enemy soldiers. Finally, shields are almost always made of wood - which is an extreamly poor conductor, so even if you had a massive capacitor you still wouldn't electricute the guy holding it, let alone his friends.
Its a cute theory, but sadly the physics just doesn't stack up.