Sorry if this has been addressed before, but with the new patch and Hotfix, secondary and tertiary weapons become extremely lethal, so much that I equipped my pre 1918 battleships with 9" guns and as much 6" and 2" guns as possible, combined with a high speed. With the new penetration values I would just go close in and hammer even heavily armored battleships with my 6" guns. In a fight of 10 BB vs 10BB my ships repeatedly annihilated the enemy, in most cases without losing a single ship. Also interesting were the hit probabilities at very close (<2500 m) range: Main guns 1%, 6" 8%, 2" 15%.
While this was actually fun to play, historically its a bit out of whack...