Invoking the Tsurugi of Muramasa causes a fear effect similar to reading scare monsters and gives a temporary effect equivalent to increase damage (possibly only on hits made with the Tsurugi, possibly with any weapon).

It was also pointed out that triggering a temporary effect by invoking could get tedious. Another suggestion was to give it some sort of passive fear-causing effect when wielded (in addition to the one-time scare when invoking it).