Creating New Weapons with Armorer

So, if I’m understanding the Skills and Factors system correctly, if an armorer wanted to make a deadly crossbow with the Armorer skill, it would be as follows:

Crossbow
Deadly (4) + Missile (5) = Ob 9

Is this correct, and if so, ouch (though it would be a powerful weapon)?

Isn’t it Ob3 for Deadly (it’s the third option in the list, since ‘Short and Quick’ are a single option), and Ob4 for Missile, for a total of Ob 7?

Paw-to-paw says start counting at one, and missile weapons start counting at 2. I read this as:

Paw-to-paw (start counting at 1)
(1) - Short and Quick (2) - Useful (3) - Deadly (4)

Missile (start counting at 2)
(2) - Spear (3) - Thrown (4) - Missile (5)

Is this not correct?

Yeah, a deadly missile is Ob 9. Tap your Nature and get help.

Cool, just wanted clarification I was reading the (start counting at) skills correctly…thanks.