Placing it down, Eldrian repeated this two more times. One he did not add any dot and the other he planned to add and remove mana from the dot. With the one with a dot, he confirmed that he could effectively control the runes, like a switch.
With the first one, he confirmed how long it could stay 'on', and with the one without a dot he tested if he could still activate the runes. While he was able, he found that the cost of doing so was the cost of activating the runes.
Granted, this cost was lessened by the material it was engraved on, however, the fact that the dot could make the cost just 1MP was massive. This small change might make it able to use an item's ability with near no cost.
Observing what was going on with mana sense, Myropsis on the other hand used a variant of inspection to allow her to see the flow of mana inside items, the two found that the mithril was actively being drained. Which was not ideal.