There is a widely known swiss army knife pen trick which was popularized by Felix Immler. The trick is to use the parcel hook tool to trap the swiss army ballpoint ink pen so that the pen is more comfortable to hold while you write with it.
I figured out my own unique version of that trick. My version still works if your swiss army knife doesn't have a parcel hook. As far as I know, nobody else has shared this before.
Step 1:
Pull out the pen and open the corkscrew.
Step 2:
Carefully twist/rotate the pen through the center of the corkscrew as shown in the picture.
Step 3:
As shown in the picture, close the corkscrew so that the back of the pen is pushed against the plastic handle/scale where the tiny straight pin hole is. This will keep the pen stable. Now you can write with it while holding the swiss army knife like a pen body.
When you are done, simply open the corkscrew and twist/rotate the pen in the opposite direction to remove the pen from the corkscrew. This part can actually be a little tricky at first. You need to learn the correct alignment of the gray plastic piece on the pen to allow it to untwist from the corkscrew. Once you figure that out, the pen comes out easily.
I figured out my own unique version of that trick. My version still works if your swiss army knife doesn't have a parcel hook. As far as I know, nobody else has shared this before.
Step 1:

Pull out the pen and open the corkscrew.
Step 2:

Carefully twist/rotate the pen through the center of the corkscrew as shown in the picture.
Step 3:

As shown in the picture, close the corkscrew so that the back of the pen is pushed against the plastic handle/scale where the tiny straight pin hole is. This will keep the pen stable. Now you can write with it while holding the swiss army knife like a pen body.
When you are done, simply open the corkscrew and twist/rotate the pen in the opposite direction to remove the pen from the corkscrew. This part can actually be a little tricky at first. You need to learn the correct alignment of the gray plastic piece on the pen to allow it to untwist from the corkscrew. Once you figure that out, the pen comes out easily.