Ruthana is literally the definition of frail and pathetic, at least in regards to physical stature and physical ability. Mentally, she's probably one of my strongest characters.
First off, Ruthana is 5'7"- not terrible, but about average height for a woman from her country. She has no advantage there.
Second, Ruthana has very little muscle. Seeing as she's sitting hunched over a desk almost all day, sorting through papers and government deals, plus the fact that she's literally running a country and getting update 24/7, it's not like she's going to have a whole lot of time to get up and walk around, let alone carry out a whole exercise regimen.
Third, Ruthana's colleagues love to bully her. Obviously their constant berating takes its toll on her health, both physical and mental. And it's not even criticism of her leadership. The ringleader of the whole thing, Saxona Rhodes, couldn't find anything that was actually wrong with Ruthana's skills, and so instead decided to insult her...body.
Rhodes tells Klaus that she's "too fat", or "looking not a pound over 200", or some other nonsense like that. Even though she's massively underweight and atrophied, Ruthana subconsciously heeds her subordinate's complaints, and refrains from eating.
Ruthana has this weird complex where she feels like if she caves to others' demands and meets their needs, that somehow they'll respect her and listen to her when she needs them to. That just ain't how the world works, honey. Sadly, Ruthana's blind hope and optimism is only going to be her downfall.
In spite of her occasionally wishy-washy behavior and weird complexes, though, Ruthana is extremely competent. Not only had she endured years worth of pressure and stress, as well as depression and incredible losses, but she had also risen out of the darkness that held onto her for almost her entire adult life. Ruthana had found that sometimes, the best way to combat the mean-spirited and malevolent creatures in the world is to distance yourself from them, and surround yourself with the benevolent. Ruthana had been voted in as Prime Minister of Prectorium, much to the rage of her former enemies.