Aegis Expert Feat

You are particularly adept at forming and manipulating your enhancing Aegis of magical effects. You gain the following benefits:

Prerequisite: 2nd level Spellblade

• You can select an Aegis effect that costs a 1st level spell slot, gaining that feature without expending a spell slot. You can change your selection when you complete a long rest when you prepare your Aegis effects.
• At the end of a long rest when you activate your Aegis effects, you gain a number of temporary hit points equal to the total levels of spell slots expended on empowering it (including the free one granted by this feature).
• During a short rest, you can exchange one Aegis effect for another of the same spell slot cost. Once you do this, you cannot do so again until you complete a long rest.

Source: KT Spellblade Class