Well... There's some perfectly okay boring rope on a shop counter right nearby

You look for something to tie the warriormaiden up with, and you spot some rope lying on the workbench of a nearby artisan shop, so you walk over and get it. As you make your way back through the crowd, you wonder to yourself why you're taking such a straightforward approach, rather than... Say... Stripping some hapless female onlooker naked and using her clothes as restraints. Maybe you're getting a little old.

You return to the knight to start tying some knots.