Welding skill on its own does not, because it is general to the trade. What can qualify is his knowledge of the company's own cladding sequence, alignment procedure and equipment, which exists inside this employer rather than in the industry at large.
The employer's process, not the applicant's trade
Hypothetical example: a Grand Bay-Westfield shop describes its fabrication supervisor as one of the best welders in Atlantic Canada. Even if that is true, it points the officer at a general labour-market judgement, which is not the L-1B question and invites the reply that skilled welders can be hired locally. The productive description is narrower.
He wrote the shop's wear-plate cladding sequence for a specific alloy pairing, holds the parameter set that makes it repeatable, developed the alignment method used on curved conveyor runs, and is the only person who has commissioned the design at full scale. That knowledge is advanced within the organization and not commonly held outside it. Building the petition around a named, documented company process turns an argument about how good he is into a question about what he knows, which is the question the category actually asks.