Garuda is far from weak thanks to her insane self sustain, however a few things irks me in her design :
Bloodletting is as boring and basic as it can get : bleed yourself, get energy. There is little to no interactions or skills involved, you just slap it around blood altars for free energy. It's also ridiculously good at self sustaining you
Her passive doesn't work that well for several reasons : first because it's too dangerous to bleed yourself too much during high level missions, but also because a lot of times you might end up being healed without your concent by allies. In my case, I usually end up ignoring her passive and just focus on surviving : Seeking Talons does a better job at improving my damage output anyway thanks to the bleed debuff thing.
EDIT : Actually her passive works well if you run a QT build, unwanted heals may still be a small issue though.
Talking about Seeking Talons : it seriously bothers me that the cost of that ability isn't impacted by how much you charge it. Pressing 4 without charge shouldn't cost you 100 base energy just for hitting some stuff in a straight line.
Dread Mirror and Blood Altar both involves you jumping at high speed to a distant enemy, which is effectively an overlap. It's not the worst overlap in the world though : we're far from a Bastille VS. Vortex level of awful overlapping, but it's there. IMO it would be better if you wouldn't have to jump on an enemy when using Dread Mirror. It may definitely not look as flashy, but IMO it's better if summoning your shield doesn't require you to get out of position.
Her talons are available as a melee option if you do not equip a melee weapon, but they're just kinda there really. They're just slightly above average and doesn't grant you any particularly noticeable benefit (aside from the fact that you may be able to hit enemies in the rift if you happen to play with a Limbo in your squad, at least this is what the wiki says). You're very likely better out with the current top tier melee weapon of the moment. They also follow the exalted weapon modding rules while having very little of the advantages given to exalted weapons, but hey at least they won't consume energy.
Despite her already strong-ish state, I think it would be very appreciated if the following changes were made :
Base cost of Seeking Talons should be reduced to 50 energy, and ramp up to 100 energy at full charge.
Bloodletting should be a bit riskier. Consider temporarily making it disable your healing. As a compensation, add a CC effect to enemies around it so it's not THAT risky : maybe you could blind them with your blood. This would also, sort of, fix one of your issues with your passive.
If such a change are made, we may need a way to pick up the quantity of health we want to sacrifice. 50% of health regardless of choice may not be ideal.
Remove the mobility component of Dread Mirror. It's counter intuitive to make you move out of position to get a frontal shield.
Consider giving to Garuda's Talons the following properties :
Heavily increased finisher damage, both for stealth and ground finishers.
100% gore chance (if it's not already the case).