Neat find, and a good ID. That's what it is sure enough.
There’s more detailed information abut the how and the why of “Gibson’s Medicinal Spoon” at the link below, taken from contemporary documentation (but note that the Royal Society refers to Charles Gibson as ‘G. Gibson’ in error):
(deleted by mod, rule infraction)
You haven’t said whether yours is silver or pewter, but I’m assuming not silver since you haven’t mentioned any hallmarks. The spoons were made by several manufacturers in silver from 1828, and then pewter versions began appearing around 1835.
The word "warranted" does not usually in itself give you much in the way of dating information. It has two potential meanings: either just as an indication that the quality or longevity of the piece is backed by a guarantee; or as an indication that a maker has been given permission for something. In this case, it might be an acknowledgement that Dixon was using Gibson's design by permission or under license.
Although the rest of the wording is a bit worn to the right hand side, it doesn't look as if there's a letter 'S' on the end of the word 'SON', and the symmetry of the spacing also suggests that it's 'SON' and not ‘SONS’. That would put it between c.1823-1835 from a company naming point of view, and further narrowed down since the spoon wasn’t invented until 1828.
