Should I deal with Edgar?

Hint 1 of 6:

If you refuse his deal, he will attack and kill you.

Hint 2 of 6:

Agree to work with Edgar at first.

Hint 3 of 6:

If you retrieve the chest and take it back to the mine machinery room, Edgar
will be waiting for you.

Hint 4 of 6:

He does not keep his promises.

Hint 5 of 6:

Edgar is crazy and will not remember your favor the next time you see him.

Hint 6 of 6:

Getting the chest is not necessary.