wind been so chilling, it would have soon drained the heat

[suprunp]

From the moment they entered the cloud, the ever-present moisture began to accumulate on Eragon’s skin and soak into his woolen clothes, weighing them down. It was an annoyance he could have ignored had not the combination of water and wind been so chilling, it would have soon drained the heat from his limbs and killed him.
(C. Paolini; Inheritance)

I think that I should read it as follows:
"[...] had not the combination of water and wind been so chilling that it would have soon drained the heat from his limbs and killed him."
Am I right?

Thanks.

[5jj]

I think it would read better with a comma after 'ignored' and no comma after 'chilling'. 'That' after 'chilling' is possible, but not essential, in my opinion.