This weapon is unique to enemies and is not available to the player. As such, information is sometimes speculation or guesswork.
The Brazer Welder is a 
Grineer tool used by Drudge Brazers. As with the Foreman Hammer and the Scrapper Grinder, its primary use is for ship construction and maintenance, making it ill-suited for combat. Although its name implies that it is used for smelting, it deals primarily 
Puncture damage.