I took a peek in the Construction Set, and it turns out Master Aryon is a pretty good marksman. Now the obvious explanation for this is: his class is “sorcerer,” and marksmanship is one of the minor skills of the sorcerer class. So it was probably just automatically generated based on his level and class. Honestly his restoration of 90 is much more out of place. But still! I would have never imagined Aryon pulling a bow before.
Doc suggested that maybe he pulled a bow when he was a young man, as part of an adventuring and/or mercenary career, and he still keeps it up as a hobby. Hence this WIP: