Angels are dedicated support by default. They're not much to look at in terms of Stats, but they can offer a selection of rare and powerful spells.
Protect increases a unit's survivability by their maximum Health, Focus gives them more AP for more options, and with Strengthen in the mix, their ally is ready to rampage with impunity. However it's their list of healing spells that really makes them shine. From Heal, GreaterHeal and even the powerful FullHeal, to the rare MassHeal and Martyr that no other standard Hybrid Species get, Angels are the envy of any healer.
However they are quite fragile, and while most other units suffering similar problems have skills to run (i.e. Teleport) or tank (i.e. ShadowForm), Angels don't get anything of the sort. They may be Agile fliers who can Slow onAttack, but with only 3 base Speed they're not getting very far.
Thankfully they can equip a full range of equipment. They'll particularly benefit from a ranged weapon. Since they're fliers they can also be upsized for power without interfering with movement when exploring. However what they really need is a solid range of genetic traits to boost their Stats.
You could try breeding a Magic Level Type. They'll get less Mana but slightly more Health, and their best stat is their Magic anyway. With flight, Agile, ManaDrain, and the fact they only get one fixed skill leaving plenty of room for other spells, they can effectively be turned into self-sufficient mobile artillery, though it's debatable whether an Angel would perform better in that role than a Butterfly would.
- Very fragile and weak but also very mobile with access to very strong supportive spells.