Found the word in the internet when I searched for "tempern". Webster's confirms:
anneal: to heat and then cool (as steel and glass) usu. for softening and making less brittle.

getempert - tempered

I don't know malleablize.

malleablize seems to be somthing like dethrone in French, mayby some slang word in Porn business. And Yes, malleablize is in LEO too, but I didn't hear it before.

Thank you all for your help, anneal is the correct translation I think. In the meantime, I think I also solved the "sexy" connotation. From http://matse1.mse.uiuc.edu/~tw/metals/glos.html (a technical glossary, which is actually very useful and includes "annealing"), under malleable: "can be hammered into a sheet". So "to malleablize" should be some kind of porn slang for "to masturbate" ! Case closed, I think...

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