I would say that they may attract lightning as a side effect of the power they hold. Even heat lightning would be drawn to it. During any normal rain, the odds of getting struck by lightning are greatly increased. If in a thunderstorm, you can pretty much guarantee they will get struck.
The affect would be much like a discharge when getting struck. The wielder is totally unaffected except for the flash but those around them could get hit by the random balls of lightning and have to deal with the concussion.
During a fight, this would be an awesome sight.
If you are trying to sneak up on somebody or are on the run, well, it is basically a beacon to where you are.
All said, during the raining season, you would be a very lonely traveler as I wouldn't go anywhere near you. Go to Comment
I like the idea of having to catch lightning. Thats pretty cool. I would really like to see more of the ecology of this steel. Does it exist naturally, if it does: what is it like there? Are there any myths or rumors about it, or famous people who used it to do something great (even if untrue)? What is some cool local folklore about it? Is it hard to mine or purify, and what special precautions have to be taken by what group of people. Does it affect local trade anywhere. Can it be used in any alchemical process. Frankensteins monster?
Little bits of detail like that really take a solid idea, and make it a must have idea.
The evil shark people link is broken, but I like this idea, but I just happen to like the idea of whales as being more powerful and a threat to humanity, rather than it's victim. I can see the black leviathans coexisting in varying states of peace and war with things like Cheka's krakens.
Certain trees have sap that is filled with magical potential. Their sap is harvested and distilled down to produce various types of potions, much like maple syrup is collected in some areas. The magical effects of these syrupy potions are often fairly trivial; perhaps they simply cause the imbiber to grow hair more quickly, summon butterflies, or walk a few inches above the floor. People enjoy the syrup as a flavoring, instead of imbibing it for its magical powers.