An inventory system is coming soon to Wyrmsun! In the next patch, inventories will be made available for all persistent heroes (including custom ones), as well as regular Stonelords and Gryphon Riders. Heroes will now be able to carry healing potions with them - as well as equippable items. When AI units die, they will now have a chance to drop items like weapons and shields, which when equipped provide your hero with a bonus (replacing the bonus given by the equivalent technology upgrade).
Below is a screenshot of the custom hero Virfir with his unique throwing axe, Toporik:
If you don't want to wait for the patch to be released, you can try out the patch beta right now by going to Wyrmsun's properties in your games library, and then in the "Betas" tab choosing the patch 1.8.0 beta.