First, your answer:
/equip (gear slot) "Item Name (+1/2/3 inculded)"
/equip main "Weathered War Axe"
/equip body "Bronze Chainmail +1"
and so on. The system is case sensitive, last I checked. Remember to add the (colour) that comes after the item description, and the relevant bonus on the end. Two (or more) word item names are to be enclosed in quotes, one word item names can stand without quotes, just like abilities.
Also, I believe your website uses old information- offhand abilities (like shield bash) no longer need the (sub) command added.
Second, the official post on this is here