"I cannot see what you are cautioning against, quite, but if you wish..."
An unusually dangerous-looking knife extrudes from the wall, with an arm-length double-edged blade and hefty solid hilt set with a giant red-translucent stone at the bottom. Merrin may not recognize it as a ruby if she's used to clear unclouded synthetics for corundum.
Albe presents it to her, hilt-first, holding it by the blade herself, without apparent trepidation.