At risk of sounding non committal, the relevance of certain fascist paraphernalia, both material and verbal, is more a matter of post fascism than fascism itself. By that I mean that the people who have recently - or let's say over twenty years ago - made use of fascist symbols and refrains (not that there is shortage of those for the Regime produced an impressive amount of ideological bric-à-brac) rarely do so in the same context and for the same reasons they were used within the fascist regime.

The answer to your general question should perhaps come more through an analysis of neo-fascist european movements - something that is beyond my actual expertise. Nonetheless it is clear that, already in the aftermath of WW2 those elements invested in "reworking" some "core values" of fascism into a political system did so in a manner resembling more cultural appropriation than a genuine imitation.

Neo-fascism usually does not claim to be fascism; but rather the preservation of certain "fascist ideals" or even merely "national ideals" or just "ideals", accordind to how loosely an association with fascism one wants to create.

As for the term itself, both the previous answer (albeit brief) and the article linked appear substantially correct. It was a motto of the Arditi - loosely translated with "I don't fucking care" or any equally impolite and matter of fact observation.

Indifference in the face of death was one of the elements the Arditi - the special formations of the Italian Army during the Great War - claimed as their founding character. Violence of course was another; and the Arditi iconography, with skulls and knives, became popular first during the last stages of the conflict; thanks also to the ideal support of relatively popular intellectuals like Gabriele D'Annunzio and futurists like Marinetti. The connections between the futurist (political) movement and the Arditi led soon after the war to the creation of a sort of movement - anticipated already in the summer of 1918 by men like Mario Carli with his Arditofuturista that he sung as the new man of the war from the periodical Roma futurista.

Done with the actual war, the Arditi found various ways to keep the war experience going. The most noteworthy being their partecipation to the Fiume occupation under the leadership of D'Annunzio. But also a few more individualistic episodes of violence - by which I mean that they were usually fairly well organized actions but also carried out by small fringe groups, rather than the result of a unified movement. Among those most famous the fire set to the Hotel Balkan on July 1920, when the Arditi had already begun to cross over and merge with the newborn Fascist movement.

The clear anti-slavic connotation of the most famous Arditi enterprise (anti-Slovene in fact) may cast some doubt over the idea that the First Lady has more or less overtly chosen to call back to Italian Fascism.

Nonetheless those action squads and their "values" were soon diluted into the sea of the growing fascist numbers - from a few thousands to over 200,000 members during 1920-21. It is not a surprise that the mottoes, the skulls and knives, the songs - while becoming part of the regime folk liturgy - would also retain an aura of "true ideal fascism". The fascism of the origins, when being fascist was an act of bravery, of defiance, not a convenient accomodation or a career choice.

And that aura was somewhat restored in 1943 when the new generation of fascism made what neo-fascists would perhaps call the "honorable" choice of assisting the Germans in their occupation of Italy.

That's more or less the idea behind the use of fascist symbols in post war years (but again, I think much more could be said by someone whose focus is on this specific period).

Overall, I would posit that this is more a matter of fashion history - i.e how themes and symbols of "political" nature or just random words have come to embellish our clothing. And the entire thing just a poor choice of clothing.