Gyre and Gimble
|Two quick blades joined by a chain. Swinging one compels the wielder to swing the other, as if they have minds of their own.|
+5 quick blade
Gyre and Gimble is an unusual weapon - thematically two separate weapons, they are treated in game as a single two-handed weapon that just happens to get twice as many attacks as a normal quick blade would. As quick blades already attack extraordinarily fast anyway, this amounts to an absurd number of hits before the enemy can react to you. At mindelay (8 Short Blades skill), you'll essentially be getting in an attack every 1.5 auts. When hasted, this goes up to an attack every aut. In short, you'll be attacking very quickly.
However, the actual effectiveness of these attacks depends on two things: your slaying bonuses and the enemy's AC. A quick blade doesn't deal very much damage per hit unless it has a set damage brand, like distortion, electrocution, or pain. The vorpal brand is slightly better than nothing, but still one of the worst options available for a quick blade. This issue doesn't matter much for low-AC opponents, as you'll simply spread the damage out over several attacks, but against high-AC opponents you'll be barely scratching them. Enough slaying bonuses, liberal use of potions of might, and easy access to berserking will overcome this issue, allowing Gyre and Gimble to be effective against armoured foes and absolutely devastating against the unarmoured. Good luck finding those slaying sources, however.
Alternatively, if you happen to have a reliable, infinite source of invisibility (or enemy blindness), Gyre and Gimble function as a phenomenally deadly source of stabbing damage. When invisi-stabbing your way through a pack of enemies that can't see invisible, you'll be delivering lethal blows at terrifying speed, regardless of their AC. Again though, this is not tremendously more useful than invisi-stabbing with other short blades.
Whether or not it's worth sacrificing use of your off-hand is up to you, but a well-branded, fully-enchanted quick blade and buckler of resistance may be the smarter choice in some cases. Formicids, of course, don't have to worry about losing their shield slot.
Gyre and Gimble is a reference to the poem "Jabberwocky" by Lewis Carrol.
Gyre and Gimble were added in 0.16.