Why diameter matters
A handrail that's too thin doesn't give a secure, confident grip; one that's too thick is hard for smaller hands (children, elderly users) to close around properly. There's a comfortable middle range most hands can grip securely — worth discussing explicitly with your fabricator rather than defaulting to whatever pipe stock happens to be on hand.
Finish and grip
Mirror finish can feel slippery, especially when hands are damp; hairline/brushed finish offers slightly more grip texture. For handrails specifically — not just decorative balusters — this is a genuine practical consideration, not just an aesthetic one.
Wood-capped handrails
Some installations pair an SS structural rail with a wood grip cap on top — this softens the cold, hard feel of bare steel and can improve comfort, at the cost of needing occasional wood maintenance.
Who this matters most for
Homes with elderly residents or young children benefit most from deliberate handrail ergonomics — this is worth raising explicitly if either applies to your household.