Well this is how normally T/W ratio is calculated of most of the fighters for people to understand, in layman's term, as already posted by BB above, T/W ratio differs as per situations. With weapon load, majority of the planes whose T/W ratio is being shown as 1 or greater goes down.
Here check this link, all the T/W ratios have been calculated with empty weight and fuel weight added, weapon load isn't.
Thrust-to-weight ratio - Wikipedia, the free encyclopedia
So with weapon load the T/W of JF-17 will also go down, similarly for other planes too.
Yeah, the engine's specs are better then what is normally told, why it is being done, well its natural and whether Chinese did it or it has come from the Russians in that way, well no comment for now about that.