As stated in the description, this is at 1:6th scale, which in case you don't know means it's for 1:6 action figures, which are usually around 30cm high…
I can't put my hands on any of my old legos right now, but not only are legos only about 4cm high, but they're also totally disproportionate and don't fit any kind of scale (same for technic lego figures, only about 9cm or so), so no, it isn't compatible.
If you're looking for lego sized swords, there are plenty around on this site I'm sure.
If you're looking specifically for Trunks sword however, then feel free to contact me via PM about your exact need and I'll see if I can proportionate it to lego-size.
Good day :)