In very simple terms: The pen succeeds most effectively and minimal losses of every kind on its own, but the sword will always lose more if not ACTUALLY LOSE because head on never works without difficulty or problems--or death. But the pen's logical, strategical qualities can pair with the forceful sword qualities to also succeed in anything, a most deadly duo. But the point: The pen succeeds on its own and with the sword, the sword needs the pen to be just as effective or else the sword will have losses if used on its own. PS: For everyone who thinks the pen and sword means fencing with a dude that has an actual pen against an actual sword, you are all wrong. The pen symbolises stradegy, logic, communication, flexibility, planning, wit and sometimes peacemaking (SOMETIMES), the sword symbolises reactions, head first decisions, brawn, recklessness, and sometimes war (again---SOMETIMES). The sword acts first, thinks later, the pen thinks first, acts later.
I, personally, am a sword enthusiast, and amateur sword smith. I definitely could think of more than one way to write or sign my name with a sword, and even more with a dagger. However, you can't use a pen for more than a crude shank. Yes, it is true a pen writes better than a sword or dagger, however a sword is better at writing than a pen is at stabbing.
Of course the sword is mightier. When face to face the sword can strike down the pen at any time. The pen just sits in its comfy office bribing other swords with money to kill each other. But the sword is completely self-sufficent. The pen needs the sword to survive and thrive. The sword can survive on its own.
And ideas are bulletproof. The only way the sword may truly triumph over the pen is to get another pen to overwrite the first pen. The calling upon another pen makes the sword irrelevant. Therefore, if an idea is out there, it needs to be disproved, not cut down. If it's official political party thing, then it's forbidden fruit, which opens up another can of worms.
A sword is powerful, but rationally thinking it cuts down one foe at a time. A pen can take out many people, manipulate thought processes, and rally allies to come fight alongside them. Either one is useless if the wielder does not understand or know what they are doing though.