Tedd's Glove (not to be confused with Tedd's Gauntlet.)is a glove which Tedd uses to program magic watches. It was also called the glove of enchanting at least once by Dan. Tedd intended to build it as device capable of enchant watches using computer by itself, only using the wielder as power source. However, Pandora told him that it's Tedd's ability of being a seer that enchants the watches and while the technology helps with preparing and holding data shaping the spell, so the glove would enchant with exact spell as described by those data, it would not work for anyone who isn't also seer (or possibly wandmaker).
We first see the glove when Grace leaves to secretly meet Adrian Raven in Death Sentence 4. After that, we are supposed to first see the glove when Tedd prepares watches with cat form for Sarah. We first see it to program watches when Tedd prepares non-furry cat form.
It seems that Tedd is preparing the spell on the computer, transfers the data to glove and the spell then works exactly as those data describe. Pandora mentions that it's a way to more easily customize spells ; it's even possible that some spells (clone forms ?) would be too complicated to program otherwise.