May be SW is meaning Shockproof and Waterproof. Recently,
Stylus 1050 SW: Stylus 1050 SW
Shockproof (5ft)
Waterproof (10ft)
Freezeproof
Stylus 1030 SW:
Shockproof (6.6ft)
Waterproof (33ft)
3.6x Wide-Angle Zoom Lens
Stylus 850 SW:
Shockproof (5ft)
Waterproof (10ft)
Freezeproof
Stylus 790 SW:
Shockproof (5ft)
Waterproof (10ft)
Freezeproof
Stylus 770 SW:
Shockproof (5ft)
Waterproof (33ft)
2.5" HyperCrystal™ LCD
Source: Official website