All Weftworld humanoids have magical ability at a similar, very weak, level. Since they can't learn to do much that's useful, not everyone uses it, and often it's only used ceremonially.
Unlike Shade, Instar does not subdivide people into 'spellcasters' and 'magic workers'. There is no dissemination of spells, so effectively no casters.
All magic is performed by 'working', though there is no improvisation: workings follow precise and time-honoured acceptable rituals. Permission to innovate is confined to suitable authorities.
This adds another offence to the list of transgressions Weft is clocking up by associating with Suitov.