It is 6w before power supply losses and then a tube that is likely under 20% efficient. The primary thing that gets you with welding is the fraction of a second before an auto darkening lens activates. It is a tiny amount of time, but it adds up. Or all those times you accidentally touch the tungsten to the pool with tig. Welding has a wide spectrum, but it is the power that matters most here. The frequency and power are two separate and unrelated things. Like your microwave and WiFi are both 2.4 GHz machines. Your WiFi in your home router is limited to 100 milliwatts and is totally harmless. Your microwave needs a Faraday cage built in to avoid cooking you from the inside out because it is likely around 1500 watts. At 220nm the frequency doesn’t pass through skin or eye fluid and the power output of the light is low. Seriously, try getting into things like telescope filters where you’re trying to isolate certain frequencies. It is challenging at these frequencies to find anything that is transparent. Of all of my science books, my optics handbook is by far the largest and hardest for me to follow. That isn’t saying much, but I have built my own telescope electronics and eyepieces, along with hobby electronics, designing and etching circuit boards and photolithography using various UV lights I have built. Six watts is nothing major. I would be more concerned about how limited of an area one light can cover.
That information is mentioned in the video. It is out there if you were to look instead of arguing on a rhetorical forum with a user that has nothing to do with the product or any vested interest in this whatsoever and simply tried to share something to be positive and invest their time in the community here. Interactions like this are why people tend to regret their efforts and post and interact less, or at least that is the impact such interactions have on me. You really need better self awareness here.