Bhagavad Gita

ನಿಮಿತ್ತಾನಿ ಚ ಪಶ್ಯಾಮಿ ವಿಪರೀತಾನಿ ಕೇಶವ ।
ನಚ ಶ್ರೇಯೋsನುಪಶ್ಯಾಮಿ ಹತ್ವಾ ಸ್ವಜನಮಾಹವೇ ॥೩೧॥
nimittāni ca paśyāmi viparītāni keśava |
naca śreyosnupaśyāmi hatvā svajanamāhave ||31||

Sloka 1:31
Gist of the sloka:
O Keshava, I am only seeing bad omens. I am unable to visualize if it means bad or good for my people.
Even though the omens were known to Arjuna even before entering the battlefield, he now recollects them and tries to use it as a reason to convince Lord Krishna. Anxiety which had taken hold of Arjuna makes him use all his wit and reasons to achieve his objective.
The world is interlinked in multiple ways. From a smallest atom to the huge universe everything is linked and is mathematical [astronomy, astrophysics]. This is the cause for the science of astrology, reading of omens, panchanga [almanac] etc., as they are all interlinked and can be deduced mathematically.
Incidents which we call as ‘accidents/coincidence’ are actually neither ‘accidental’ nor ‘coincidental’. It only means that we do not know as to how the events happened but are events planned by Master of the Universe, Lord Krishna.
Let’s take a look at the various omens in Mahabharatha. Elephants, horses were showing signs of tears before entering the battlefield. Foxes were roaming around the camps. This is in alignment with the general observations that animals seem to sense disasters much before it happens.
There were two eclipses during the war. One on the 5th day and another on 18th day. All within the span of 18 days of the war. This indicated very destructive war with major loss of lives. This in fact was mentioned to Emperor Yudhishthira by Sage Veda Vyasa much before, by indicating that the Emperor son Duryodhana would be cause of major worldly destruction and loss of lives.
Remembering all these omens, Arjuna addresses Lord Krishna as “Keshava”. Lord Krishna means “one who has descended to Earth to give joyfulness and strength”. Keshava is split into 3 parts - Ka+esha+va. Ka meaning one who gives strength to Brahman for creation, esha means one who gives strength to Shankara for destruction of the created world. Together it means one who gives the strength for both creation and destruction of the world. In other words, meaning one who rules the created universe and is responsible for it.
The reason Arjuna uses the word ‘Keshava’ to address Lord Krishna is in a way trying to remind the Lord Krishna that he is the one who has descended to give happiness and strength to the world, but now he is trying to force a war and destruction on the same world.
Please also note, that on the 18th day of the war, the Dwarapara yuga ended and Kali age started.
Arjuna continues to come up with various reasoning to back away from his commitment to war. We see this in the succeeding stanzas.