Sorry, but installing arch linux doesn't mean you are some computer master. You are just following instruction on a wiki. Anyone could install arch linux if felt like, and wanted to put some time into it.
Some people make arch linux their personality especially the forum.
You could argue that Debian is more lightweight since it doesn't roll development libraries and binaries into the same package. It's really a question of lightweight in what sense? Disk utilization? IO? RAM? Computation?
People usually mean lightweight as in small package count. I dunno how many packages Debian installs by default, especially if you choose the minimal distro, but the arch install I used at school had like 700 packages and I did most of my schoolwork on it. It's meaningful in the sense that the less packages you have installed, the less likely the system will break after an update and the less upkeep you need. Resource wise, Arch is as lightweight as whatever DE you're rocking. Obviously a WM setup with no window compositing is going to be super light on resources but you can have one of those on Debian no problem.