Controlling such a weapon or item gives you control, down to molecular control where applicable, over the element. How would such a setting advance? Where would technology, war and civilization be 50 years on?
I think the key here is simple- how well would people utilize such fundamental powers? I mean, say you've got a flaming sword with control over fire, right? Ranking various applications of it from 1-10, on the basis of cunning/vision...
1: My sword's on fire, bitches! Still want to fight me?
2: My sword's on fire, bitches! Clearly I am destined to be a glorious leader!
3: God has granted me control over fire, bitches! Clearly I am destined to be a glorious leader! Pay no attention to the way I always hold my sword in my left hand when I exercise this innate god-given ability!
4: Oh look. The room is on fire, yet none of the flames seem to be touching me. Shame the same doesn't go for you.
5: Use oil and flaming arrows, we'll end this siege tonight. Trust me, it doesn't matter that there was a downpour this morning.
6: Oh look, this city I was visiting incognito is now burning down despite spirited attempts to quell the flames. Guess they aren't gonna be in very good shape when my army rolls in next week.
7: We can make our forges' flames burn far hotter than than would normally be possible. Give our metalsmiths a year or two and we'll be churning out equipment that's miles beyond anything anyone else can offer.
8: Get your scholars, we are going to analyze the crap out of this thing and figure out how to track down more of these items.
9: Get your scholars, we are going to analyze the crap out of this thing and figure out how to *make* more of these items.
10: Get your scientists. We are going to analyze the crap out of this thing so as to figure out how *magic itself* works. Hop to!
Of course, by the time I finished writing out that list, the thread had fallen off page 10 of the imageboard and been deleted. Good thing I thought to CTRL-C the text before hitting "submit".