Has anyone gone for the obivous weakness to light - a mirror? If you can reflect the attacks elsewhere this guy is useless.
Edit:
You can also change light by putting it through a crystal and bending the ray to create a rainbow.
Edit:
Also you can block light with a black object since the colour black (not really a colour) absorbs all formed of light.
I am personally fond of ppl sharing their opinions, views making up their own theories and expalining them to us.
So basically what I wish to say is that I am glad that you are looking for a potential weakness of the light logia fruit.
All I would add to the thus far arguments about mirrors, crystals and similar stuff is…
The guy travels at the speed of light, if someone can start deflecting attacks with the speed of light with some mirrors and similar stuff then hats off, then again this is manga and not everything goes by the rules...
Just if we look at the ppl who have so far faced him, we can notice that before they are punched they basically dont even realise untill after...the guy just punches at the speed of light, I guess non of them is able to even notice the kick, so any kind of dodging doesnt happen and most certanly there is no room for mirror stuff...
But we ll see how Oda goes with it...
Thje light fruit is just powerful and when Kizaru says speed is weight, he says it right. At the speed of light even the lightest things contain power of massive proportions...
And perhaps an interesting detail. In an ultra cold atomic gass speed of light can be reduced to 17 m/s, must say, that when seeing that data I imediately thought of Aokiji even if he has the slightest connection to it heh.
So anyway its my opinion that its not his lasers that present a problem not even him being logia. I mean its kind of hard to hit someone even if you have seastone whatever if he is able to move at the speed of light and make blows with that speed.
Blue