I think mid-to-late 20s in DA:O is probably ballpark, even without the toolset. I say that because its said in DA:O that Leliana is older than she looks, which to me rules out her being in her early 20s.
Yeah, she does say she looks younger in the conversation with Wynne, but Wynne actually tells her at the beginning of that banter "I can't believe you've been through so much for someone so young."
I honestly think if Leliana was like 28-33 in Origins it would've been an exaggeration on Wynne's part. Here's the actual conversation:
I, myself put her at 34-35 in Inquisition.
- Wynne: It is sometimes so hard to believe that you have been through so much, at such a young age.
- Leliana: I think I look younger than I am.
- Wynne: Yes... yes, that is possible. When I was your age I was just about ready to take on my first apprentice.
- Wynne: In hindsight, perhaps I should have waited a few more years. I was arrogant, my confidence bolstered by my youth.
- Leliana: It is so hard to imagine, seeing you now.
- Wynne: Oh, I've had some two decades or so to grow mellow. Believe me, back then I was quite... prickly.