Slap Psynergy is utility Psynergy from Golden Sun: Dark Dawn. Despite being a utility Psynergy, it is possible to be used in battle. Although it can be used by equipping the Slap Glove (which is only temporarily in your possession), Sveta permanently has it.
In the field, Slap conjures a gloved, white hand which strikes whatever it is aimed at. In battle, it does the same, except the hand is larger, and targets an enemy. Slap costs 4 PP to use.