The pen is mightier than the sword

Literally.

...

Okay, maybe not literally.

As with most items I purchase online, I had my new SD card shipped to my office. However, as I lack the means to a sharp blade at the office, I was left with a rather dull blade from a Swiss army knife.

With it, I futilely tried to cut open the child-proof packaging of the memory card. When that failed, I grabbed a pen and traced along the lines made by the Swiss army knife, as was able to break through the plastic.

Couldn't have done that as easily with the Swiss army knife, so yeah, that makes the pen "mightier." Obviously, that's not what they had in mind when they came up with the phrase...