[RPG] Can a thrown weapon be picked up

There are no rules for this, but there is a lot reasons to use some best guessing to handle it.

Since 4e is a miniatures based system, I note the direction and type of missile used.

If it is hand-throw I figure that it travels the same distance beyond the target that it was thrown to get to the target. This gives me a simple way of tracking without complicating my life at the table. Remember that magic items that can be thrown will return to the thrower's hand.

If it is a fired weapon, like a crossbow, sling, or bow, then it travels 3 times the distance between the firer and their target. Again, simple and easy to track when you are at the table.

If then there is a reason to look for missile items during or after combat, it is simply a DC check vs. perception. This can be modified by visibility, terrain, combat conditions or weather.

I use easy DC values for hand thrown items and moderate for fired items. I do this to simulate breakage of the items. The searcher may find the item but it can not be reused. Again simple and relatively accurate for game purposes. Really difficult terrain or conditions that could have items be lost or break moves the DC value up to the next higher bracket.

A battlemind doesn't have lots of options in that regard, but there are a few with which you may be able to get close to what you want.

Note that other than your suggestion I haven't found a way to significantly increase the range at which a battlemind can mark, so most suggestions here are just workarounds or ideas which could help with increased mobility and so on.

The highest range I could find among battlemind powers with a quick Compendium search was melee weapon +3 reach (Dimensional Ambush^[DDI]) respectively close blast 3 (Obsidian Shield^[DDI]) - the rest was at most close burst 2.

Class features, powers and feats:

• Wild Focus^[DDI]: Battlemind class feature; free action, encounter, close burst 10; pull target Cha modifier squares and mark it till EOYNT.
• Speed of Thought^[DDI]: Battlemind class feature; free action, encounter; move 3 + Cha modifier squares, can be used even when surprised. Can be enhanced to 5 + Cha modifier squares with Improved Speed of Thought^[DDI].
• Persistent Harrier^[DDI]: Battlemind class feature; immediate reaction, encounter, melee weapon; when enemy hits or misses you, you attack him back (even if the target is outside your melee reach) and teleport adjacent to it.
• Iron Trap^[DDI]: Githzerai racial feat; when enemy misses you because of Iron Mind racial feature, the enemy is marked and you gain combat advantage until EOYNT.
• Demand's Reach^[DDI]: Battlemind feat, paragon tier; increase Battlemind's Demand to close burst 5.

Equipment:

• Predatory Weapon^[DDI]: Weapon power; free action, encounter; when hitting with the weapon mark one target within 5 quares until EOYNT.
• Farslayer Weapon^[DDI]: Weapon power; standard action, at-will; make melee basic attack up to 5 squares away.
• Greater Dancing Weapon^[DDI]: Weapon power; minor action, at-will; animate weapon (direct with move action, fly speed 6, must see target squares), while you can see the weapon you can make melee weapon attacks through it (counting the weapon's square as origin square instead of your square).
• Blade of the Eldritch Knight^[DDI]: Weapon property; when using a standard action to make a melee attack increase reach to 5 for that attack.
• Planesplitter Weapon^[DDI]: Weapon power; free action, encounter; when making a melee attack increase weapon reach by +2 squares.

In any case you might want to take a look at the "Beyond Bodily Brutality: the Basics of Building Battleminds" handbook on the WotC boards.

And yes, your assumption is correct. Taking Student of the Sword^[DDI] would allow you to mark any enemy once per encounter with any attack that is made with the selected weapon type (one-handed melee or two-handed melee) regardless of hit or miss.