The iconography, representational style, and even religious function of the bodhisattva, Vajrapani has changed considerably over the centuries of South Asian art, in contrast to other deities whose iconography remained quite fixed. In his earliest representations from the ancient region of Gandhara, Vajrapani is depicted as a muscular elderly figure holding a double-lozenge-form vajra; such representations may have been influenced by Hellenistic depictions of the Graeco-Roman deity, Zeus/Jupiter, who was also represented in similar form wielding a thunderbolt. In later images from the Swat Valley and Kashmir, Vajrapani is shown in human form with his hand resting on the head of a smaller, anthropomorphized representation of the vajra, Vajrapurusha; this depiction of Vajrapani had a profound influence on early Nepalese sculpture, and a cult of worship of Vajrapurusha in his own right developed in the Kathmandu Valley. With the rise of Vajrayana Buddhism in Northeastern India in the beginning of the Pala Dynasty (8th-12th century), Vajrapani became a meditational deity, wrathful in appearance, and such forms became prevalent in the Tibetan Buddhist tradition. The iconography of Vajrapani often overlaps with the Hindu deity, Indra, and it is likely aspects of Indra were incorporated into the iconography and function of Vajrapani with the development of Mahayana Buddhism.
The present depiction of Vajrapani is represented as a bodhisattva in human form. He stands in slight tribhanga, presenting the vajra in his lowered left hand. At the center of his forehead is a circular urna, distinguishing the present figure from a depiction of Indra, who is often represented in similar format. In Nepal, where the Hindu and Buddhist populations worshipped side by side, often with significant intersection of the two religions, the syncretism of the iconography of the two deities is not surprising.
Compare the present figure with a related image in the collection of the National Palace Museum, Beijing, illustrated in Buddhist Statues in Tibet: The Complete Collection of Treasures of the Palace Museum, Hong Kong, 2003, p. 77, no. 74. The Palace Museum example, roughly the same size as the present work, displays physiognomy and iconography similar to the Alsdorf example, including the characteristic tripartite crown. Illustrating the creative variation of Nepalese sculptors, the Palace Museum example depicts Vajrapani holding the vajra vertically in contrast to the present work, where Vajrapani presents the vajra horizontally.
Compare, also, with a figure, alternately identified as Manjushri Siddhaikavira, Padmapani, or Ratnapani, at The Norton Simon Foundation (F.72.42.2), illustrated by U. von Schroeder in Indo-Tibetan Bronzes, Hong Kong, 1983, p. 321, no. 82D. The Norton Simon Ratnapani also displays physiognomy similar to the Alsdorf Vajrapani, and the details of the dhoti, including the simple incising of the hem and the hanging folds of drapery, evince a similar date and location of manufacture. The similarities between the Norton Simon Ratnapani and the Aldsdorf Vajrapani can also be seen in the representation of the face, with full, pursed lips, heavy-lidded and downcast eyes, incised eyebrows and simple, circular, incised urna.