gunblade leblanc is one of the most toxic things in league of legends, if not the most.
on a champion like leblanc, there are few downsides to itemizing gunblade. I realize that it is an expensive item, but its an item that is just too good on leblanc.
I recently played against a leblanc player who played extremely poorly. missing a large percentage of skillshots, bad dives and bad trades, going so far as not winning lane against a matchup in which she is heavily favored and while receiving a heavy amount of jungler assistance. she outsustained me on a champion which is meant for sustainability. then, later in the game, her damage was too high for our team to handle, and she was able to itemize some tank items against our team while continuing to have high damage.
it gives leblanc sustain, extra burst on an already obscenely bursty kit, and stronger AA damage on a champ that never needed it. i feel it may even be a stronger one item powerspike than trinity force on irelia.
i realize that WOTA was removed from the game because it was problematic on vlad, but gunblade on leblanc is a much larger problem. honorable mention to ahri and any other champs that i might be missing which abuse gunblade far more readily than vlad ever abused WOTA
then again, this is probably an unpopular opinion due to how popular leblanc and ahri are as champions.