Select the "Vault Menu" option at the main menu. Then, go to the "Weapon Acquisitions" menu. There are hints on obtaining the fourth and fifth weapons, but only for Gracia, Kojiro Sasaki, Toshiee Maeda, Yoshimoto Imagawa, Katsuiee Shibata, and Motochika Chokosokabe. To obtain other characters hints, import the Samurai Warriors 2 disc.