For all her strengths, there are just as many weaknesses that have been present since birth, or that have developed over the years of her existence.
Of all, the most prominent is the highly aggressive and acute form of photo-sensitivity that her kind share; the result of which is an allergy to ultraviolet radiation, causing her great pain when exposed to sunlight which manifests in burns and blistering upon the skin (she does not burst into flames as some fictional tales recount). Likewise, she finds it extremely discomforting to look into indirect sunlight as it strains her eyes. This can be overcome with the proper protective measures, specialized armors and equipment to prevent ultraviolet radiation from being absorbed, though the most common preventative measure is relegating all activities to night. Prolonged exposure to ultraviolet radiation effectively negates her healing capabilities, requiring medical attention.
Many species are what can be described as hemovoric, or as having a hemovore diet, resulting in the need to feed upon the blood of an individual. This is likewise a required need; and though she is capable of suppressing the need, she finds it difficult to do so for extended periods.
It is this hunger that can at times cause her to lock herself away from others, or to ensure that there is a 'sacrificial' individual near to prevent her from what could be described as 'turning feral'. Most times she ensures that her hunger is sated by devouring those that she defeats in combat, primarily force users.
While most activity is relegated to the hours between twilight and dawn, or the general activities aboard a vessel in the void of space; what little sleep she does manage to garner is often interrupted. For even her, at one time had a family, and that sleep is interrupted by the constant night terrors of an event she relives; the destruction of her sister by her own hands. This has resulted (even with her capabilities), in general fatigue and loss of sleep, though the primary affliction this has caused is a lack of connection. She can not, as many can, form lasting bonds (also resulting from her continued biological immortality).
Though she is capable of imparting her gift upon others, it is an occurrence that happens rarely due in part to those that agree often dying with an hour of being bitten. There are only very few individuals who are capable of surviving the process, and she's not met any whom are capable.
Strangely enough she has developed an allergic reaction to silver. While many 'silver allergies' are in fact nickle allergies (from the process of silver plated jewelry), hers is definitively a silver allergy. Much like the allergic reaction to ultraviolet radiation, prolonged exposure to silver upon unprotected flesh results in irritation, rashes, or burns depending on the exact amount of time that has passed. However these injuries are not as easily healed, requiring immediate medical attention (if treatment is not administered, this can leave to Silver Poisoning and ultimately death).
The rage of a mother is a terrible thing to witness, though in the case of Amelia it is one that is unleashed upon others. If she was to see Natalia become injured, be it something minor like a cut, or a major wound; her rage would claim her senses. Tearing into the enemy, she would focus upon the singular act of reaching Natalia just to protect her little girl from further harm. Even ignoring any injuries she would take in the process.
While she is highly resistant to a variety of toxins and poisons, there is one that has a great effect upon her, be it ingested or introduce to her blood stream. While Nightshade is highly lethal to a lesser individual of her species; it causes paralysis in Amelia, with higher doses extending that paralysis. Additionally, an oddity of her species is how Spice (any variant) would affect her. If she is introduced to it, it effectively shuts off her healing capabilities for a few hours. Prolonged exposure to Spice would effectively shut off her healing capabilities until it were flushed from her system.
She is still coming to terms with her new connection to the force - thus there are moments when she losses control - incapable of reigning in her powers as they lash out; much like her younger sister had lashed out years ago. Though her Force capabilities are more reigned in when she is calm - they are more unruly and more prone to strike out in those moments of pure rage, great sorrow or anxiety.