Well, it's true. Here [1] is the corresponding law, here [2] is wikipedia with some expamples what counts as passive weapons (plastic film, basecaps reinforced with plastic, gasmasks, knee pads, … ) and here [3] is a case where a paramedic was sentenced for wearing a helmet.

[1] https://dejure.org/gesetze/VersG/17a.html

[2] https://de.wikipedia.org/wiki/Schutzwaffe

[3] www.labournet.de/interventionen/grundrechte/grundrechte-all/demonstrationsrecht/schutz-durch-selbstschutz-demonstrationssanitaeter-wurde-wegen-vermummung-und-passivbewaffnung-verurteilt/

To [3] it is worth to add, that the civil paramedics usualy come from and are part of the (leftwing) scene, where the demonstrants are coming from, so they are not exatly like the Red Cross. So are viewed by the police as enemies as well. And that the person was freed of all charges in the next instance.

(still, it is outrageous, that he was charged in the first place)

"that sounds absurd."

I know, thats why I prefer to read the news via The Onion or similar newspapers ...