Greven : 'However, at the moment, I cannot think of any historical example of the time period where a province was given away without a war, a royal inheritence or an abandonment by the original power (the owner didn't care enough about the territory to claim it). Any historians out there to help me out?'
I've got one other example of provinces given as a gift. But maybe it can be said to be only an abandonment, as you said before.
In 1492-1493, Charles VIII of France wanted to be free of any english, austrian or spanish intervention in France while he intervened in Italia to claim for the Napoli crown. So he gave back Franche-Comté and Artois to Maximilian of Habsburgs, and Roussillon to Ferdinand of Aragon. These provinces had been conquered under his father Louis XI. But Spain and Habsburgs never really accepted this previous conquest.
Actually, it was not a pure gift. He received 2 things in exchange : officially gold and bristle gifts, unofficially Maximilian had to abandon his claim on Britanny. Maximilian could have claimed because of his short marriage with Anne of Britanny (now married to Charles VIII). With England, Charles VIII bought neutrality with money only. And of course, he expected Austria, Spain and England to stay neutral during his military intervention in the Peninsula. But I'm not sure this last thing was written in the treaties ; that may explain why Spain didn't stay neutral.
Best regards
Raphaël