When equipping the Dual Venomshanks gear, the left sword is not welded correctly to your left arm. While all dual swords simply have an offset from the main sword on your profiles, unlike the dual counterparts of Darkheart & Illumina, Dual Venomshanks broke at some point, and no longer fits R6/R15 poses.
Expected behavior
This is what the expected result is, which is from a Wayback Machine of my old profile snapshot in 2015.
As a temporary workaround, until gears are eventually revamped, it would be nice if the left sword was realigned to fit standard R6 & R15 blocky avatars, like it does in the picture above. It will not fit every scaling preset possible today, but it would allow for it to remain the same as it used to before a Roblox change broke it at some point, with its desired appearance for Classic characters.