Your pen is a Sheaffer Balance.
First, you need to put the feed back into the pen. Trying to remove a section with nib and feed out can lead to a crushed section because there is nothing in the middle to support the section as you grip it.
Soaking will not do anything for you, except perhaps to get water up inside the barrel which will cause the pressure bar to rust. The reason is that water won't go where it needs to (between barrel and section), and what is most likely holding the section in the barrel is not water soluble.
The section is a slip fit. You will need section pliers and a heat source to get the section out. These were often secured with some shellac put on the section before being inserted into the barrel. Shellac softens with heat. Warm gently,It wiggle slightly, try to turn the section to loosen. It is possible to heat the barrel to the point where instead of the section loosening, you soften the celluloid instead and shear off the barrel if you get too aggressive.
Take a moment and read my articles on tools and seeing with your fingers. I also recommend reading Richard Binders site for tips on repairs, and if you intend to do more, buying a copy of the Marshall and Oldfield book on pen repair.