I have been reading about the Masters who seal the Chancery reports.
I wonder if it is a variation of the following for example si(gi)l(a)vi, do may read in English to "Master of it is to confirm that"
sigillo, sigillare, sigillavi, sigillatus
#22
verb
conjugation: 1st conjugation
Definitions:
(DEP form also known)
confirm
seal
seal-up
Age: Medieval (11th-15th centuries)
Area: Legal, Government, Tax, Financial, Political, Titles
Geography: All or none
Frequency: 2 or 3 citations
Source: Latham, “Revised Medieval Word List”, 1980