However, another key distinction listed in the Wikipedia article is that the “Geneva Conventions declare that mercenaries are not recognized as legitimate combatants and do not have to be granted the same legal protections as captured service personnel of the armed forces.” So it’s an even riskier business.
While not what you’re asking for, but fun fact, in Asia, this sort of paradox is represented by the story of the all-piercing spear and the unpierceable shield in Chinese philosophy. So in Chinese and Japanese, the word for ‘paradox’ or ‘contradiction’ literally means ‘spear-shield’ (矛盾).