ToME: the Tales of Maj'Eyal

I found several sweet one-handed weapons and tried to convert them into a steamsaw. But I only got a subset offered in the build dialog.
I looks like only weapons with damage-type Physical can be converted into steamsaws. Looking into the code with my limited lua knowledge seems to confirm this.

But there are fixedart steamsaws with other damage-types, so what is the rationale for the limitation?

Fixedarts don't respect the normal item rules anyway. I guess the call was made that random steamsaws do not spawn with egos that modify the element type, and so it was also decided that you wouldn't be able to change those that have a different element damage?

They were modified to only spawn with phys bleed because rare items often spawned w/ a random element that you don't really want due to how their skills work, other elements just don't produce the same bleed effect.