Okay,
There are some intricacies when dealing with throwing weapons, So let's get those out of the way first.
They are intended to be gargoyle only, But with the use of a SkillBall you can get up to 120 throwing skill (with appropriate powerscrolls). I believe you can get a 120 powerscroll for throwing by killing gargoyles outside Ver Lor Reg (Gargoyle City in Ilshenar) and collecting Gargoyle Horns.
Throwing weapons have an interesting ranged system, they have a maximum range and a "sweet spot" In the given example on UOGuide's throwing post:
Underthrown - If, while equipped, a weapon has a maximum range of six tiles, and a player throws at a player two tiles away (too close) they have a Hit Chance penalty of 12%, but no damage reduction.
Perfect - Maximum range of six tiles, thrown a distance of four tiles. No Hit Chance penalty, no damage reduction
Overthrown - Maximum range of six tiles, thrown a distance of six tiles. No Hit Chance penalty, but 47% damage reduction
However, Bows do not have this penalty.
You can get a property called "Velocity" on bows, that increases damage the further you are from your target however.
Now that we are on the subject, let's talk about Properties. Bows/Thrown weapons are generally Single Target/PvP weapons. it is very difficult to make an AoE Bow setup work correctly due to the lack of a whirlwind like attack. So you're going to be looking for something like this:
Leeches are capped at a lower level than on melee weapons due to the fact that you are generally further away from your enemies.
We will look at the Composite Bow, and the Soul Glaive for this as they are the most common (due to having Armor Ignore) and happily, each has the same base speed.
According to UOGuide Leeches for a ranged weapon at 4s speed with no swing speed increase cap at 50%
So you're going to want something along the lines of (Base level 1 weapon)
45+ HLL/HML/HSL
45+ Damage Increase
45+ Hit Spell (optional but really nice)
45+ Hit Lower Attack
45+ Hit Lower Defense
These are listed in order of priority. HLA and HLD are not required, but for a single target weapon provide a large amount of extra defense/offense
Once you had that you would deed one-handed, spell channeling, UBWS (So you can stack swords instead of archery). and then level the weapon and add Lightning (or another hit spell if Lightning already existed) and then either another hit spell or something else to your liking.
So basically my ideal bow would be as follows
50 HLL
50 HML
50 HSL
50 Lightning
50 Magic Arrow
50 Fireball
50 Hit Lower Attack
50 Hit Lower Defense
Spell Channeling (Deed)
One-Handed (Deed)
Self-Repair 5 (Deed)
Velocity 50% (Deed)
And then for sockets likely Triple Slash and im not sure what else you would use.
But as long as you can get those properties up in the 44-50 range, that would be a killer weapon for use on things like Peerless, Mean Dragons, etc.
If any vets would chime in on this, and let me know whether im going in the right direction, because i dont have any single target weapons at the moment.