Umm, no. WS 1 hits anything above WS2 on 5+, and it's hit by everything on 3+.
asarnil has ws 7,which means ws 3 his him on 5+,and he hits ws 6 or lower on a 3+.
If you're having asarnil fight ws3 chaff, you'd be correct. But also wasting asarnil's power as a duelist.
Against ws 4 it functions as a - 1 to hit item.
Against Ws 7 (most combat Lords) it makes them hit you on 5+ and makes you hit on 3+, serving as a +1 to hit for you, -1 for them.
Against the rare ws 8+, it becomes even better, because it makes them hit on 5,instead of 3. I.e -2 to hit.
It's not great, but the only situation where a -1 to hit item is better is when fighting chaff, because it makes them hit on a 6+.