A quote from this discussion:

"The font is called ’Larish’ and was indeed drawn specially for Secession identity which was developed together with Willi Schmid, in 2007-2008. Its appearence is inspired by an old prints from Vienna of late 19th century. Even it is not re-drawn typeface, its shape it true to the spirit to its example."

(The actual font name appears to be Larisch Alte.)

Finally redrawm Larish Alte has been released.
http://www.radimpesko.com/fonts/larish-alte