I don't want to give out numbers, no but he is VERY powerful.
Though his Force attack rating is not going to be as high as Sienar's or Adelmo's. He can use Fling, for sure, and pretty well, but he's not going to rule the galaxy with that power. His true talents are elsewhere.
Well, that's not fair on either Sienar or Adelmo, who both have/had many other talents. But Ascar is fully controlled and rational.
What Ascar probably has the highest of is effective Force Defence.
Ah, well, look at it from the point of view of what you have learned since.
Ascar thought Kuylen was obsessed and out of control. He tried to convince him not to bother with the Mausoleum. Once it became clear that there was no stopping that obsession, Ascar thought it very unwise to get caught up on it.
When all is said and done, does he look so wrong?
Galder probably would have done similar in that situation, save his own hide rather than get pinned for having helped obsessive criminals.
I haven't actually thought much about how Galder would respond to Kuylen if the issue of the Mausoleum came up. That was an IMMENSE let down for Kuylen, and we could have seen it coming if he had not been so damn driven...