stickler

intoilija puhekieltä A referee or adjudicator at a fight, wrestling match, duel, etc. who ensures fair play. (defdate)
(RQ:Flr Mntgn Essay), II.27:

In ancient time they were wont to employ third persons as sticklers, to see no treachery or disorder were used, and to beare witnes of the combates successe.

Basilius, the judge, appointed sticklers and trumpets whom the others should obey.

Our former chiefs, like sticklers of the war, / First sought to inflame the parties, then to poise.

Lexicographers are sticklers for correct language.

The Tory or High-church were the greatest sticklers against the exorbitant proceedings of King James II.