The pen is mightier than the sword is a proverb or saying.
It was used by Edward George Bulwer-Lytton:
Beneath the rule of men entirely great
The pen is mightier than the sword.
(The Oxford Dictionary of Phrase, Saying and Quotation)
Heads must roll is a threat to execute those responsible. It may be used figuratively when people are forced to resign.
Set your sights on is an expression which comes from the use of view-finders on guns to improve the aim. It can mean to be determined to obtain goods or fulfil an ambition.
Sabotaged is a word I have commented on previously.
Outmanoeuvre is used about debate and diplomacy as well as in the field of war. Manoeuvres are the systematic movement of troops and equipment. The winning side has done this better and outmanoeuvred the enemy.
Don’t put your head above the parapet!
probably started out as an order to bowmen fighting on the battlements of a castle. Now it is often used to advise against standing out from the crowd (lest you attract unwanted attention). Perhaps this is what bloggers are trying to do – not the unwanted bit!
Get out of sight!
A sharp-shooter is accurate at picking out targets.
Shell-shocked was the mental state of many soldiers returning from World War 1. At first this was not recognised as a mental illness and sufferers were punished. Now it is described as post traumatic stress disorder. People still find it difficult to talk about mental health issues. There is a useful website here.
Taking French leave and going absent without leave (AWOL) do not have the same meaning. Brewer explains taking French leave as taking without asking leave (permission) or giving any form of payment, from the behaviour of French armies during invasions.
Confined to barracks is a punishment for misbehaviour for soldiers.
A shot in the dark is unpredictable in its outcome and has come to mean a guess and in particular an accurate one.
Mission impossible is a negative phrase.
That has ramifications sounds as if it belongs here, but is about branches and branching out. Fortifications make defences stronger.
Although this is Part 3 of the vocabulary of war, I long for the day when, “They will beat their swords into ploughshares and their spears into pruning hooks. Nation will not take up sword against nation, nor will they train for war anymore.” Isaiah 2:4 (NIV)
A two-edged sword cuts on both sides. Hebrews 4:12