Currently every weapon that has exotic skill generates a new specialisation.
German Errata has the list below (see page 11, topic 97 of https://www.shadowrun6.de/downloads/errata/errate_sr6_grundregelwerk.pdf )

• brawling (war_fan, horizon_flynn_dcom_garotte) “Handgemenge Waffen”

• whips (bullwhip, monofilament_whip, manriki_chain, yoyo_hardened, yoyo_bladed, yoyo_monofil) “Peitschen”

• chainsaws (ash_arms_standard_combat_chainsaw, ash_arms_monofilament_combat_chainsaw, under_micro_combat_chainsaw) “Kettensägen”

• launchers (subtype="LAUNCHERS", under_grenade_launcher, under_micro_bolo_launcher, under_grapple_gun_launcher) “Werfer”

• air (ares_s3_super_squirt, parashield_dart_pistol, parashield_dart_rifle, narcojet_hornet) “Druckluftwaffen”

• spray (ares_charybdis, ares_scylla, hell_turtle, shiawase_blazer) “Sprühwaffen”

• laser (crimson_wasp, red_fox) “Laserwaffen”

• emitter (pulse) “Energiewaffen”
  Note1: Shields are used with "close combat" not "exotic"
  Note2: horizon_flynn_dcom* weapons are used with normal firearms or close_combat, except horizon_flynn_dcom_garotte
  Note3: Underbarrel weapons: under_micro_bolo_launcher (exotic/launchers), under_grapple_gun_launcher (exotic/launchers), under_micro_combat_chainsaw (exotic/chainsaws), under_grenade_launcher (exotic/launchers), under_shotgun (firearms/shotguns)

Challenge is that characters, which have taken a specialisation which will no longer exist after the reduction need to regain their karma so they can re-choose (or automatically get the right new specialisation)