What's the difference between ", from which ~" and ", from it ~"?

Question

1. You can then open the chest, and from it take as much money as you please.
2. You can then open the chest, and from which take as much money as you please.

If no.2 is possible in grammar, what's the difference between the two in meaning?

Answer 1

1. You can then open the chest, and from it take as much money as you please.

This means that you can take as much money as you want from the chest.

Stylistically, from it is nonrestrictive information in this particular construction. The sentence could be written without it and still be understood:

You can then open the chest, and take as much money as you please.

Or the optional information could be included with the use of parentheses:

You can then open the chest, and (from it) take as much money as you please.

Therefore, paired commas would be the common way of styling the sentence:

You can then open the chest, and, from it, take as much money as you please.

If the from it were essential to the sentence, it would normally be rephrased in one of a few ways:

You can then open the chest, and take from it as much money as you please.
You can then open the chest, and take as much money from it as you please.
You can then open the chest, and take as much money as you please from it.

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2. You can then open the chest, and from which take as much money as you please.

If from which were treated as the same type of nonrestrictive information as from it, it could also be rephrased in the following ways:

You can then open the chest, and (from which) take as much money as you please.
You can then open the chest, and, from which, take as much money as you please.

However, while this makes sense, it's awkward and unidiomatic. Using from which in this specific construction is nonstandard (from it would be preferred).

The use of from which does not parallel the use of from it. It should not simply replace the other phrase while the rest of the sentence remains the same. Nor can it really serve as nonrestrictive information.

Even when being used to express restrictive information, it needs to be used as part of a dependent clause in this particular construction:

You can then open the chest, from which you can take as much money as you please.

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In short, and idiomatically, from it can be used to convey both nonrestrictive and restrictive information, in sentences with two independent clauses joined by a conjunction:

✔ You can then open the chest, and, from it, take as much money as you please.
✔ You can then open the chest, and take from it as much money as you please.

Meanwhile, from which would normally only be used to convey restrictive information in a sentence with an independent clause followed by a dependent clause:

✔ You can then open the chest, from which you can take as much money as you please.

Answer 2

I don't think that No. 1 is wrong, but it sounds unnatural to me. I would suggest instead

You can then open the chest, and take as much money as you please from it.

Or

You can then open the chest, and take as much money from it as you please.

No. 2 is not grammatical. I would suggest instead

You can then open the chest, from which you can take as much money as you please.

Both 'from which' and 'from it' specify where you can take the money from, but they require different constructions.