This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 釰 is uncertain. It visually combines 金 (metal) and 刃 (blade), but the original meaning and formation are unclear.
The kanji shows metal 金 beside a blade 刃, suggesting something like a metal blade or edge, but its actual meaning is not recorded.
For ジツ, imagine a dull blade that needs a jolt of sharpening: jitsu -> ジツ, tying to the kun-reading にぶい (dull).