Eisenschwert

The Eisenschwert (アイゼンシュヴェルト Aizenshuveruto) is a technologically enhanced sword that can transform into a long sword, a double-bladed short sword, or a triple-bladed dagger. It was developed by Sigismund Eisenberg.

Etymology
Eisenschwert is a combination of German eisen, "iron," and schwert, "sword." It follows the naming pattern of Eisenberg.