HI Lee i'm just looking to upgrade my wiper's and arm's so i've been looking for part numbers and i came across your numbers and i also found some part numbers in the Seat Leon Useful Part Numbers listing for Modifications threadThe aero blades can be bought to fit the regular "hook" arms.
Standard wiper arm with "hook" aeros
Golf aero wipers
S 1J2 955 425B wiper
S 1J2 955 426B wiper
1J2 955 409D arm
1J2 955 410D arm
Prices for the blades were about £25.