While holding a weapon that bears this rune, you can activate the rune as a bonus action to cause the weapon to double in size for 1 minute. You can only activate the rune while holding the weapon and you if you let go of the weapon, the effect ends.

For the duration, the weapon gains the heavy property if it doesn’t already have it (but is otherwise magically able to be wielded with ease), and the weapon’s base damage dice are doubled. The weapon also adds +2 to your AC

Once activated, this rune can’t be used again until 8 hours have passed.