Shade 5 might be OK for gas welding with Oxy Acetylene, but not for arc. Arc will require at least shade 8, for low currnent TIG. Shade 11 would be a better bet for arc, with factor 50 sunscreen on exposed skin. Seriously, though, just get a full face helmet.
A auto dark helmet is all of $40 these days, provide full face protection, and adjustable shading from about 9-14.
Why anyone would try to use #5 cutting glasses for welding is beyond me.
FWIW I have (2) pairs of those, one on the plasma table, and other for hand cutting.