In 1575 they were admitted by the council of Frankfurt in spite of the Marx brothers's protests, and on 7 March 1607, they were officially recognised by Rudolf II, although they had been acknowledged to be equally capable long before.
In their Deutsches Wörterbuch, the Brothers Grimm hold it plausible that it derives from the custom of pinning feathers to one's hat or lance, but the coat of arms accorded to the brotherhood by Rudolf II displays two arms each holding a quill (schreibfeder), inducing the Grimms to speculate that the brotherhood may merely have originated as the fencing guild of the professional scribes.
But also (188ab) 'schreib mit dinten' so sicht wie blut, 'die feder' must ihm oben schweben und solt es kosten sein junges leben: "write with ink that looks like blood, the feder (Fechtfeder, but also "quill") must sway above him, even if it should cost his young life" Federfechterei came to mean flashy mock-combat in general, thus, in an anonymous 1697 work called des träumenden Pasquini kluge Staatsphantasien, we read ... damit der herzog von Savoien ein spiegelfechten mit dem marechal de Catinat in Piemont anstellen, selbigem aber nicht viel weher thun solte, als wenn die Lucas- und Marcusbrüder mit ihrer federfechterei sich die köpfe ein wenig blutig schlagen und darbei den zuschauern die beutel leeren, so gut sie können: "... so that the duke of Savoy undertook a bout of sham-fencing with the marechal de Catinat in Piemont, without doing more hurt to the latter as when the brethren of Luke and Mark with their federfechterei bloody each others heads a little while emptying the pockets of the onlookers as well as they may" (p. 323).
Once posting his notice at the city's Rathaus, making his demonstration, and (presumably) impressing the council (by fighting a number of persons who presented themselves to fence the reviewee), he could be granted the use of an open space in which to teach.
Additional information can be found in the book Sechs Fechtschulen der Marxbrüder und Federfechter, by Karl Wassmannsdorff, published in Germany in 1870.