Instead of just being an Angel, you are a Nephilim, a being that is half-angel and half-human. While most would think that this would make you weaker than your Seraphim parent, it is actually the opposite case. This is because as a Nephilim, you were born with both Angelic Grace and a Human Soul. The combination of these two sources is like adding nitrous and a supercharger to a car. The human soul supercharges the Angelic Grace, making a Nephilim eventually become more powerful than the angel that sired them. Since you are half-human, you do not need a vessel to interact with the physical world; you were already born into yours.
As a Nephilim, you have inherited all the powers of your Seraphim parent, and the soul you inherited from your human parent has enhanced all your abilities far beyond those of multiple Seraphim combined, though still below an Archangel. With time (10 years), your Grace will reach the potency and power of an Archangel's Grace. You also have a few new abilities, such as life force draining and the ability to change your age as you wish.
Note that losing your Grace as a Nephilim is more dangerous than as an Angel because your Grace is what keeps your Angelic and Human sides in balance. The loss of it will cause both sides to fight each other, resulting in immense pain, sickness, weakness, and so on, until your Grace regenerates.