Thrusting and Parrying with the Hanwei/Rodell Cutting Jian

It's well-balanced for thrusting and parrying. It isn't too flexible for parrying - you'd parry with the base of the blade, anyway, which is the stiffest part.

I don't think it's too flexible for thrusting. It isn't designed for fighting armoured opponents, so rigid enough to pierce clothing with a thrust is good enough (note: try it on a cloth-wrapped water bottle).

It's a cut-and-thrust sword, and therefore a compromise. The blade needs to be wide enough to cut well, especially near the tip. There are two ways to achieve that width: you either keep the same blade weight and make the tip wide but thin, or you keep the same thickness, and make the blade wider and therefore heavier. The first gives you a cutting-oriented sword, while the second gives you a cut-thrust sword. This jian uses the second. 3.5mm near the tip isn't thin - only a bit thinner than a needle-pointed thrusting-oriented longsword (KoA's stats).