The trowel is one of the oldest tools of Freemasonry. It can be seen on both “Modern” (Carmick manuscript 1727) and “Antient” tracing boards. In some lodges (in the past) it was a tool of the Entered Apprentice. In other lodges (also nowadays) it is a Fellow Craft tool. Most of the time it is a tool of the Worshipful Master. In Emulation it is the jewel of the Charity Steward. In the Schröder Rite this is the emblem of the Guardian of the Temple. The symbol seems to have fallen largely in disuse after the 1813 fusion though, except in the USA (where it mostly stands for “brotherly love”) and Scandinavia.
Duncan’s Masonic Ritual and Monitor (1866) by Malcolm C. Duncan
In English masonry a trowel was historically used in the EA degree by the IG, but this was eventually replaced by the tool in use today (the poniard). The trowel is mentioned in the ‘Charge after Initiation’ in Emulation Ritual ‘have not thought it derogatory to their dignity to exchange the sceptre for the trowel’ effectively stating that throughout history even royalty has taken on the role of the most junior member of the Lodge (the IG).