The Doctor, unlike most heroes, doesn't have a weapon. Instead, he uses a sonic screwdriver for some very tricky situations. The sonic screwdriver has multiple functions. Of course, for one thing, it deals with the sonic issue. It could unlock a door or be a scanner. But it can do way more than that. In the video, you can see how the Doctor use it creatively, to fix everything, or even cost an explosion.
"Scanner, diagnostics, tin opener!" The sonic screwdriver could manage to do everything an adventurer needs for the incredible journey ahead!
Extend reading: A Brief History of the Doctor's Sonic Screwdriver